Stereophile Review

Electronically REPRINTED
FROM December 2010
E Q U I P M E NT
R E P O RT
Peachtree
iDecco
ART DUDLEY
D/A INTEGRATED AMPLIFIER
Peachtree iDecco D/A integrated amplifier with digital iPod dock
DESCRIPTION Solid-state integrated
amplifier with built-in D/A converter,
USB interface, and digital iPod dock.
Inputs: 1 line-level analog, 2 S/PDIF
digital (1 coax, 1 optical). D/A signal/
noise ratio: 118dB. Preamp output
impedance: <30 ohms. Amplifier
output power: 40Wpc into 6 ohms
(14.8dBW) at <1.0 % distortion.
DIMENSIONS 14.75" (380mm) W
by 5" (130mm) H by 14" (360mm)
D. Weight: 23 lbs (10.5kg).
SERIAL NUMBER OF UNIT
REVIEWED 0004184, firmware v1.1.
PRICE $999. Approximate number
of dealers: 104.
MANUFACTURER Signal Path
International, 2045 120th Avenue
NE, Bellevue, WA 98005.
Tel: (704) 391-9337.
Web: www.signalpathint.com.
www.Stereophile.com, December 2010
A
s with so many other things, from cell phones to soy milk, the idea
of a portable MP3 player was something I at first disdained, only
to later embrace with the fervor of any reformed sinner. But not so
the idea of a high-fidelity iPod dock: Given that I now carry around
several hundred high-resolution AIFF files on my own Apple iPod
Touch, the usefulness of a compatible transport seemed obvious
from the start. Look at it this way: In 1970, whenever I bought a
music recording, I could enjoy it on any player, in any room in the house. In 2010,
why shouldn’t I enjoy at least that degree of convenience and flexibility—without
resorting to a pair of tinny, uncomfortable earbuds?
So it was that Wadia Digital’s first iPod dock, the Model 170, earned its status as a
seminal product; and so, I daresay, will Peachtree Audio be recognized for pioneering yet another worthy genre with their iDecco: a perfectionist-quality iPod dock
and a similarly pedigreed digital-to-analog converter, combined with a tube-buffered
preamplifier and a 40Wpc power amplifier—all for $999.
Description
The US-designed iDecco, which is manufactured in mainland China, has its origins
in the Peachtree Nova ($1199), a similar DAC-integrated with a little more power
(80Wpc) and a lot less dock. Having earned dozens of rave reviews, including John
Marks’ writeup in “The Fifth Element” in the August 2009 Stereophile, and with retail sales nearing the 4000 mark, the Nova endures. But Peachtree’s David Solomon
P eac h tree i D ecco
now seems ready to bring the gospel of
good sound even nearer to the audioindifferent.
Solomon describes the genesis of
the iDecco: “We simply started reading RIAA statistics, and there it was:
Look what’s happening! Consumers have
changed the way they buy music, and
[the world of downloadable media files]
is where they are.”
The Peachtree iDecco is designed
around a traditional linear power supply with a toroidal transformer: Thankfully, wall warts are neither required
nor supplied. (I’ll probably never accept the idea of four-figure domestic
audio products that use the same sort
of AC adapter as a Hello Kitty portable
CD player.) For its part, the power amp
The iDecco’s tube can be switched in and out of circuit with the remote.
is built around the TDA 7293 power
MOSFET IC from ST Microelectronics, operated in class-A/B. The preamplifier’s solid-state gain stages run in
class-A, while some degree of driver-
stage buffering is conferred by a 6N1P
dual-triode tube. As in the Peachtree
Nova, the tube buffer can be switched
in and out via a pushbutton on the remote handset, a function not duplicated
measurements
T
o perform the measurements on the Peachtree
iDecco, I mostly used Stereophile’s loan sample
of the top-of-the-line Audio Precision SYS2722
system (see the January 2008 “As We See It”
and www.ap.com); for some tests, I also used my vintage
Audio Precision System One Dual Domain and the Miller
Audio Research Jitter Analyzer.
Before I did any testing of the iDecco, I ran it at onethird power into 8 ohms for an hour, which imposes the
maximum heat stress on an amplifier with a class-AB
output stage. At the end of that time, the iDecco was hot
but not bothered.
Looking first at the iDecco’s performance as a digital
decoder, a full-scale 1kHz tone clipped the amplifier’s output stage with the volume control set to 2:30. The level
from the variable preamp outputs with the tube in-circuit
was 848mV in this condition. The maximum level from
the line-level output jacks was 2.06V, sourced from a low
impedance of 10 ohms, and while both the loudspeaker
outputs and the fixed-level line outs preserved absolute
polarity for digital sources, the variable preamp outputs
inverted polarity with the tube. Other than when noted,
I continued the digital testing from the fixed line-level
outputs with the volume control set to its minimum,
to avoid stressing the iDecco’s amplifier output stage.
The iDecco locked to S/PDIF datastreams with sample
rates ranging from 32 to 96kHz, but not to data with sample
rates greater than 96kHz. The top two pairs of traces in
fig.1 show the iDecco’s D/A frequency response with
44.1kHz data (cyan, magenta traces) and 96kHz data (blue,
red) with the rear-panel Filter pushbutton set to Fast. The
response is flat and extended at both frequency extremes,
at least until the inevitable steep rolloff just below half the
sample rate. By contrast, the green and gray traces in fig.1
show the response with 44.1kHz taken from the variable
preamp outputs with the tube operating, the volume
control set to 2:00 and the Filter set to Slow, offset by 1dB
for clarity. There is now a slight (0.3dB) imbalance between
the channels and the low-frequency response is down 3dB
at 11Hz. At the other end of the spectrum, the effect of the
Slow filter is to roll off the top-octave output a little early,
the response being down 3dB at 19.5kHz.
Testing the DAC’s resolution with a swept bandpass filter
while it decoded a dithered 1kHz tone at –90dBFS gave
Fig.1 Peachtree iDecco, frequency response at –12dBFS into 100k ohms from
fixed outputs with data sampled at 44.1kHz (left channel cyan, right
magenta) and 96kHz (left blue, right red), and from variable outputs
with volume control set to 2:00 (left green, right gray). (1dB/vertical div.)
Fig.2 Peachtree iDecco, 1⁄3-octave spectrum with noise and spuriae of
dithered 1kHz tone at –90dBFS with 16-bit data (top) and 24-bit
data (bottom). (Right channel dashed.)
www.Stereophile.com, December 2010
P eac h tree i D ecco
on the iDecco’s front panel; given that
the tube is “ramped in” to the circuit—
with full rail voltage on the plates at
all times—the changeover takes only a
few seconds. Solomon says that, with
the tube switched in, “we lose about
6dB of signal/noise ratio. But I think it
sounds better.”
The D/A board is where things get
really interesting. The star of the show
is an ES9006 Sabre DAC from ESS
Technology, of Fremont, California.
According to Solomon, the Sabre DAC
reclocks the datastreams from all digital sources, and upsamples them to 24
bits and 96kHz. Solomon also says that
the iDecco’s D/A board incorporates
11 regulated power supplies of its own,
to enhance interstage isolation and thus
keep noise to a minimum.
The iDecco’s USB transceiver is
separate from the ESS Sabre DAC, and
is galvanically isolated from the rest of
prevent grounding glitches and switching noise.
The iDecco’s front panel is simple
and spare: That lucky tube gets its own
The tube buffer can be switched in
and out via a pushbutton on the
remote handset.
the board. “We learned early on we had
to do something about noise coming
off the USB cable,” Solomon says. The
USB socket and the iPod connection—
the latter is purely digital, and bypasses
the player’s headphone output—are also
transformer-coupled to the circuit, to
little window, flanked on one side by a
(motorized) volume knob, and on the
other by five illuminated source-selection buttons. All front-panel controls
are duplicated on the pleasantly rubbery remote-control handset, alongside
such extras as a Mute button and the
measurements, continued
the traces shown in fig.2. The top pair of traces were taken
at the variable preamp jacks, again set to 2:00, with 16-bit
data, and the bottom pair with 24-bit data; you can see that
the increase in bit depth drops the noise floor by 10dB or
so in the treble. There is a slight bump at the 60Hz AC line
frequency, but this is sufficiently far down in level not to be
an issue. Repeating the analysis, this time from the fixedlevel jacks with an FFT technique, gave the traces shown in
fig.3. The increase in bit depth now drops the noise floor by
18dB, which implies that the iDecco’s ESS 9600 Sabre chip
has at least 19-bit resolution. However, some harmonics of
the AC frequency can be seen with the 24-bit data (blue, red
traces), and a regular series of distortion harmonics is also
unmasked by the lowering of the noise floor. DAC linearity error with 16-bit data (not shown) was vanishingly low
to below –100dBFS, and the iDecco’s noise floor was low
enough to allow the three DC voltage levels that describe an
undithered 16-bit tone at –90.31dBFS to be readily resolved
(fig.4). With undithered 24-bit data, the result was a noisy
but otherwise well-defined sinewave (not shown).
When it came to distortion, the two line-level outputs
varied dramatically. The blue and red traces in fig.5 show the
spectrum of a full-scale 50Hz tone at the fixed-output jacks.
The second harmonic lies at –90dB (0.003%), the third at
–80dB (0.01%), and the fourth at –110dB (0.0003%). By
contrast, while the third harmonic remains at the same level
from the tubed variable-output jacks, the fourth harmonic
has risen to –90dB and, more significant, the second has
Fig.3 Peachtree iDecco, FFT-derived spectrum with noise and spuriae of
dithered 1kHz tone at –90dBFS with: 16-bit data (left channel cyan,
right magenta), 24-bit data (left blue, right red).
Fig.5 Peachtree iDecco, spectrum of 50Hz sinewave, DC–10kHz, at 0dBFS
into 100k ohms from fixed outputs (left channel blue, right red), and
from variable outputs with volume control set to 2:00 (left channel
cyan, right magenta). (Linear frequency scale.)
www.Stereophile.com, December 2010
Fig.4 Peachtree iDecco, waveform of undithered 1kHz sinewave at
–90.31dBFS, 16-bit data (left channel blue, right red).
P eac h tree i D ecco
aforementioned tube switcher. Additional buttons on the handset can be
used to control the most basic playback
functions of the iPod itself: skipping
forward or backward through various
songs (but not albums), pausing the
music, and resuming play.
The rear panel is nicely laid out, with
inputs for four of the five sources—USB
digital, coax and optical S/PDIF digital, and line-level analog—plus one pair
of preamp outputs for subwoofers or
other ancillaries, and a pair of line-level
outputs for those who might wish to
use the iDecco as a standalone DAC to
drive some other preamp or amp. Two
other items deserve mention: a twoposition switch for choosing between
soft and steep digital filter slopes, and
USB and S/PDIF digital inputs—and one pair of analog inputs.
a Jitter Bandwidth control, with Narrow and Wide settings (think of them
as fine and coarse sieves, respectively),
for use with the S/PDIF inputs.
Finally, the Peachtree iDecco is pro-
tected by an MDF “wrap” liberally
vented for heat dissipation, and finished
with a sufficiently glossy (black) paint
that I long assumed the case was made
of some sort of polymer.
measurements, continued
risen to –50dB (0.3%). In both cases, a picket fence of
very-low-level spuriae is also visible. The primary difference
between the two outputs is that, with the variable jacks, the
signal passes through a 6922 tube. It is the “bent” transfer
function of this tube that generates the even-order distortion.
Fig.6 Peachtree iDecco, HF intermodulation spectrum, Slow Filter, DC–
24kHz, 19+20kHz at 0dBFS into 100k ohms (linear frequency scale).
Fig.7 Peachtree iDecco, HF intermodulation spectrum, Fast Filter, DC–
24kHz, 19+20kHz at 0dBFS into 100k ohms (linear frequency scale).
www.Stereophile.com, December 2010
As can be seen in fig.1, the slow in “Slow Filter” refers to
the rate of the reconstruction filter’s ultrasonic rolloff. It is
generally felt that a slower rate of rolloff sounds better, but
the downside is that there is less rejection of the ultrasonic
images that result from the digitizing of the signal. This can be
seen in fig.6, which shows the spectrum of the iDecco’s fixed
outputs while it decoded 24-bit data representing an equal
mix of high-level 19 and 20kHz tones. The primary ultrasonic
image of the two tones is suppressed by just 12dB, and other
aliasing spuriae are folded down into the audioband. Switching this filter to Fast gives the spectrum shown in fig.7: the
ultrasonic images have dropped significantly in level, as have
the audioband aliasing spuriae. The primary intermodulation
product, at 1kHz, has risen slightly, to –96dB (0.0015%), but
this is still negligible in absolute terms.
The iDecco offers three choices of digital input: S/PDIF
(on coaxial and TosLink connectors), USB, and from an
iPod plugged into the top-panel dock; a second rear-panel
pushbutton selects between Wide and Narrow receiver PLL
bandwidths. The Wide setting is to allow the iDecco to successfully lock to digital sources with poor-tolerance clocks;
however, the downside is that this gives rise to increased
Fig.8 Peachtree iDecco, Wide receiver, high-resolution jitter spectrum of analog
output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled
at 229Hz, 16-bit data from SYS2722 via 15’ TosLink. Center frequency of
trace, 11.025kHz; frequency range, ±3.5kHz (left channel blue, right red).
P eac h tree i D ecco
Setup and use
Like the Naim Uniti CD/receiver before it (see my review in the March 2010
Stereophile), the Peachtree iDecco led a
nomadic existence in my home: I applied
it to four different pairs of loudspeakers
(Audio Note AN-E/SPe H/E, Wilson
Audio Sophia 3, Quad ESL, Advent
Loudspeaker) in three different rooms.
Most of my listening was done with the
first two pairs, in my listening room/office (19' long by 12' wide by 8' high).
Installation was a breeze: Once I’d
connected the iDecco’s USB input to
my Apple iMac G5 computer (OSX
10.6.2), a sound output device listed as
“USB Audio DAC” appeared in the
computer’s System Preferences window, and I duly selected it. As for its
top-mounted iPod connection, the
iDecco is supplied with four different
dock inserts, one of which fit my and
my daughter Julia’s iPod Touches to a T.
In addition to AIFF and MP3 files
from our iPods (v.4.0.2), and those plus
WAV files streamed from my computer’s copy of iTunes (v.9.2.1), I tried
bypassing the iDecco’s USB transceiver
by streaming files to a Stello U2 USB
transceiver, then on to the iDecco’s coaxial S/PDIF input by means of a Black
Cat Veloce cable (a superb product at
a bargain price of $123). I compared
the whole of the iDecco’s USB DAC
system to various outboard USB DACs
on hand, using the latter to address the
Peachtree’s single pair of line-level analog inputs (labeled Aux). I also tried my
aging Sony SCD-777ES SACD/CD
player, from both its line-level analog
outputs and its optical S/PDIF output.
I had intended to try streaming music
files direct to the iDecco’s optical input,
from the iMac’s headphone jack—which,
remarkably, is also an S/PDIF digital
output—but an optical plug adapter that
I ordered for that purpose didn’t arrive
in time. A Follow-Up may follow.
Listening
It’s often presumed that, all other things
being equal, the performance of an integrated amp is compromised compared
to the performance potential of good
separates. Take that equality from the
scene and the compromise is presumed
greater still, as with an especially cheap
measurements, continued
levels of jitter. Fig.8, for example, shows the spectrum with
the 16-bit J-Test signal fed to the iDecco via TosLink. Though
data-related jitter other than the sidebands at ±229Hz is at
the residual level, there are strong sidebands at ±1.8kHz,
and a significant widening of the central spectral peak due
to random low-frequency clock variations. The jitter level
was 519 picoseconds peak–peak, according to the Miller
Analyzer. This is still low in absolute terms, but switching to
the Narrow setting lowered the jitter level to below 200ps,
narrowed the central peak in the spectrum, eliminated the
high-frequency sidebands, and reduced all data-related
sidebands to the residual level of the test signal (fig.9),
which is superb performance.
The iDecco takes data from an iPod in digital format;
repeating the jitter test with the 16-bit J-Test signal playing on an iPod Classic 160GB gave a low 310ps of jitter.
While there were no data-related sidebands present in the
spectrum (not shown), there were sidebands of unknown
origin present at ±91 and ±816Hz. Feeding USB data from
my MacBook gave just 260ps of jitter, from sidebands
at ±1423Hz (not shown). The iDecco offers excellent
rejection of jitter, though with both iPod and USB sources
there was significant widening of the central spectral peak,
again due to the presence of random low-frequency jitter.
Examining the iDecco with the Mac’s USB Prober utility
identified the USB receiver as a “USB Audio DAC” from
“Burr Brown from TI” operating in adaptive isochronous
mode, and indicated that it accepted 16-bit data with
sample rates of 32, 44.1, and 48kHz only.
Moving on to the iDecco’s amplification section, the
output from the speaker jacks preserved polarity (ie, was
non-inverting) for digital inputs, but inverted absolute
polarity for analog signals fed to the Aux input via the tube.
The maximum gain for analog input signals was fairly low
for an integrated amplifier, at 28.7dB into 8 ohms. The Aux
input impedance was usefully high, at 48k ohms at low
and middle frequencies, dropping slightly but inconsequentially to 42k ohms at the top of the audioband.
I had to scratch my head a bit when I examined the
iDecco’s output impedance. I perform this measurement by
comparing the output voltage with the amplifier driving 8 or
4 ohms with how much that voltage rises when I remove
the load. A simple Ohm’s Law calculation then gives me the
amplifier’s output impedance (including the cables in use,
Fig.9 Peachtree iDecco, Narrow receiver, high-resolution jitter spectrum of
analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with
LSB toggled at 229Hz, 16-bit data from iPod Classic. Center frequency of
trace, 11.025kHz; frequency range, ±3.5kHz (left channel blue, right red).
Fig.10Peachtree iDecco, frequency response at 2.83V into: simulated
loudspeaker load (gray), 8 ohms (left channel blue, right red), 4
ohms (left cyan, right magenta), 2 ohms (green). (1dB/vertical div.)
www.Stereophile.com, December 2010
P eac h tree i D ecco
integrated amp. For the amp to share its
chassis and power supply with source
components—an iPod dock and a D/A
converter, perhaps?—harshens the compromise still further. So the question
becomes: How cleverly were those
compromises chosen and implemented?
In the context of the perfectionistquality gear with which I’m familiar,
the iDecco’s shortcomings were far
from severe, and had more to do with
abstract sonics than purely musical capabilities, the latter being extremely
good (a subject to which I’ll return in
a moment). The iDecco’s overall sound
was nonetheless satisfying, with a treble
range that sounded naturally extended,
lacking both the excess grit and the peculiarly chalky quality that characterizes
a great deal of budget solid-state playback gear. The opposite end of the spectrum was also well served: The lowest
piano notes and drum and synth tones
Transmigration of Souls, with Lorin Maazel leading the New York Philharmonic
(CD, Nonesuch 79816-2).
Actually, the iDecco’s most identifi-
The iDecco’s overall sound was
nonetheless satisfying, with a treble
range that sounded naturally extended.
sounded fast and well controlled, albeit
without quite the locomotive weight
one can hear from, say, a Shindo, Lamm,
Audio Note, or EAR tube amp. But the
Peachtree did a satisfying job with the
huge orchestral drum sounds and other
harrowing effects in John Adams’ On the
able shortcoming was that to which I
find myself least sensitive: It didn’t have
quite the same degree of spatial depth
as the best contemporary electronics.
I might also add that my favorite electronics, all of which are either very expensive, or very rare and thus terrifyingly
measurements, continued
of course). However, when I disconnected the load with
the iDecco, the output voltage dropped, suggesting that
the Peachtree actually has a negative output impedance of
about –0.2 ohm. This can be seen in the plot of the amplifier’s frequency response (fig.10), where the output with
the 2 ohm load (green trace) is higher than it is with 4 or 8
ohms. This is unusual, and suggests that the amplifier circuit
uses a degree of positive feedback. However, the variation
in response with our simulated speaker (gray) is very low.
Note the low-frequency rolloff in fig.1, which, at –3dB
at 55Hz, is even more extreme than that seen in the
response from the preamp outputs (fig.1, green and gray
traces). I was puzzled by this, but after some thought I
repeated the response measurements at various settings
of the volume control. The traces in fig.10, taken with the
volume control at its maximum, are repeated as the bottom pair of traces in fig.11. The other traces in this graph
were taken at progressively lower settings of the volume
control, and you can see that the iDecco’s low frequencies
are well extended at volume-control settings of 12:00 and
below. It looks as if the iDecco reduces its low-frequency
bandwidth as you increase the volume beyond 12:00, and
that this is performed in the tubed preamp section.
Fig.10 indicates that the iDecco’s ultrasonic response
extends well beyond the 200kHz limit of this graph.
This correlates with very short risetimes on its response
to a 10kHz squarewave, but there is a small degree of
overshoot with very-high-frequency ringing into lower
impedances (fig.12). Channel separation was good rather
than great, at 87dB R–L and 59dB L–R at 1kHz, as was
the wideband, unweighted signal/noise ratio (taken with
Fig.11Peachtree iDecco, frequency response at 2.83V into 8 ohms with
volume control set to (from right to left): maximum, 3:00, 2:00,
12:00, 9:00 (left channel blue, right red, 1dB/vertical div.).
Fig.13Peachtree iDecco, distortion (%) vs 1kHz continuous output power
into (from bottom to top at 1W): 8, 4 ohms.
www.Stereophile.com, December 2010
Fig.12Peachtree iDecco, small-signal 10kHz squarewave into 4 ohms.
P eac h tree i D ecco
expensive, imbue recorded music with
a little more presence, somewhat more
color, and a lot more texture than did the
iDecco. That would be true—but who in
the world would expect otherwise?
As to the iDecco’s purely musical
performance, I was impressed beyond
all reasonable expectations. The iDecco
played music with an excellent freedom
from timing distortions: Upbeat fare
such as the title track of Audra Mae’s
The Happiest Lamb (CD, Sideonedummy SD1416-2)—a more rhythmically
nuanced track than average, I daresay—
exhibited fine pacing. Even downtempo
numbers—such as Peter Rowan and
Tony Rice’s “Trespasses,” from the
Quartet album (ripped from Rounder
11661-0579-2), and Procol Harum’s
poignant “An Old English Dream,”
from The Well’s On Fire (CD, Eagle ER
20006-2)—maintained good momentum, and resisted tipping over like the
musical equivalent of a ponderous bike:
a rarity, believe it or not, among cheap
and dear equipment alike.
Of course, of the many playback
modes of which the iDecco is capable, I most looked forward to hearing
AIFF files from my iPod Touch played
through the integral iPod dock, and
comparing them with the exact same
files streamed from my iMac-iTunes
installation through the iDecco’s USB
input. I spent many a long hour doing
just that.
The results weren’t always what I expected. The distinctions weren’t huge,
by any measure, and they confounded
me further by being somewhat musicdependent. For the most part, I slightly
preferred the iMac-to-USB route, for a
number of reasons: That approach not
only rewarded me with the most open,
least opaque treble performance of which
the iDecco seemed capable, but also with
the Peachtree’s best sense of note-tonote flow—which was considerable. The
beautiful, sun-dappled melodies that fill
Elgar’s Nursery Suite, as performed by Paul
Goodwin and the English Chamber Orchestra (ripped from Harmonia Mundi
HMU 907258), were easier to trace
through the USB than through the iPod
inputs. Likewise, the subtle keyboard
wash in the background of Jeff Buckley’s
“Lilac Wine,” from Grace (ripped from
measurements, continued
the volume control at its maximum but the Aux input
shorted) at 67.5dB ref. 1W into 8 ohms. This was primarily
due to low-level spuriae at 120Hz and its harmonics that
I couldn’t eliminate by experimenting with the grounding
between the iDecco and the Audio Precision test system.
A-weighting the S/N ratio, which discounts the effects of
LF and HF noise, thus improved the result to 83dB.
Peachtree specifies the iDecco’s maximum output power
as 40Wpc into 6 ohms (14.8dBW) rather than the usual 8
ohms. However, fig.13 shows that the amplifier didn’t clip
(defined as 1% THD) until 40Wpc into 8 ohms (16dBW) and
53Wpc into 4 ohms (14.2dBW). The low-power distortion
is around 0.03%, but increases in a linear fashion with
increasing power, this due to the mainly second-harmonic
distortion introduced by the preamplifier stage (figs. 14 and
15). Intermodulation distortion with an equal mix of highfrequency tones at a level just below visible clipping on the
oscilloscope screen (fig.16) was primarily the low-order difference product, at –50dB (0.3%), again this stemming from
the tubed preamp stage; but the power-supply–related spuriae can also be seen in this graph, admittedly at a low level.
Peachtree’s iDecco may be budget-priced, but it packs a
lot of functionality into a small package. Its D/A section is
particularly impressive technically, especially regarding its
resolution and rejection of jitter, but you need to take the
output from the fixed line-level jacks to get the maximum
performance from it. As an integrated amplifier, the
iDecco’s performance is dominated by its tubed preamp
section, which introduces even-order harmonic distortion
much like that of a classic tubed amplifier. —John Atkinson
Fig.14Peachtree iDecco, 1kHz waveform at 1W into 8 ohms (top), 0.155%
THD+N; distortion and noise waveform with fundamental notched
out (bottom, not to scale).
Fig.16Peachtree iDecco, HF intermodulation spectrum, DC–24kHz,
19+20kHz at 20W peak into 8 ohms (linear frequency scale).
www.Stereophile.com, December 2010
Fig.15Peachtree iDecco, spectrum of 50Hz sinewave, DC–10kHz, at 20W
into 8 ohms (left channel blue, right red; linear frequency scale).
P eac h tree i D ecco
Columbia CK 57528), seemed more
delicate, and consequently more effective, through the USB.
But played through the iDecco’s
USB input, some music—soft acoustic
fare, for the most part—could at times
sound a bit too smooth for my tastes:
listenable, but comparatively unstirring. On guitarist David Grier’s approach to “Little Wing,” for example,
from Phillips, Grier & Flinner’s Looking Back (ripped from Compass 7 4342
2), I found myself thinking that the
sound from the iPod input gave a better feeling of (realistic) pick-on-string
noises, while most of the outboard
USB DACs I had on hand—especially
the Wavelength Cosecant ($3500)—
were even more satisfying. That said, I
suspect that the iDecco’s ultrasmooth
Sabre DAC would be more at home
in budget systems, and with music
files of less than high resolution.
A few words about the iDecco’s more
esoteric user controls: Even though it
sounded a little brighter and sharper, I
generally preferred the iDecco’s Fast filter slope, which seemed to get the most
out of note attacks, natural textures, and
the like. Also, as the iDecco’s very useful
manual would lead one to expect, digital sources that are presumed to be low
in jitter were sonically better served by
the Narrow setting of the jitter switch,
whereby music sounded a little more
substantial and detailed, and more musically purposeful and tuneful. As for that
tube switch, the differences were extraordinarily slight, but I did prefer having the
tube in-line; voices and lead instruments
then gained a shade more body and color.
Without the tube, the sounds of solo
voices were more like outlines: perimeters,
with anchor points in the bass and treble,
but missing some midrange fill.
Nova
A final performance note: Just before
writing this review, I compared the
Peachtree iDecco with a well-worn
sample of its predecessor, the Peachtree
Nova. I expected few, if any, obvious
differences, especially when driving the
more sensitive speakers at my disposal—
an expectation that was confounded,
howsoever slightly. The smoothness
that characterized the iDecco’s USB
input was, if anything, more conspicuous through the Nova, in addition to
which the latter presented a soundfield
noticeably larger than that of the less
expensive Peachtree amp. Through the
iDecco, Bob Dylan’s Highway 61 Revis-
ASSOCIATED equipment
ANALOG SOURCES Thorens TD-124 Mk.II turntable; EMT 997, Thomas Schick
tonearms; Shindo SPU, EMT OFD 25 & OFD 65, Ortofon 90th Anniversary
SPU cartridges.
DIGITAL SOURCES Ayre Acoustics QB-9, Wavelength Audio Cosecant, HRT
Music Streamer II & II+, Chord Gem USB DACs; Stello U2 USB transceiver;
Apple iMac G5 computer running Apple iTunes; Sony SCD-777 SACD/CD player.
PREAMPLIFICATION Auditorium 23 Hommage T1 step-up transformer;
Shindo Masseto, Shindo Vosne-Romanee preamplifiers.
POWER AMPLIFIERS Shindo Corton-Charlemagne & Lafon GM-70.
LOUDSPEAKERS Audio Note AN-E/SPe HE, Wilson Audio Specialties Sophia
3, Quad ESL, Advent Loudspeaker.
CABLES USB: Transparent Performance USB. Digital: Black Cat Veloce 75 ohm.
Interconnect: Audio Note AN-vx, Shindo Silver. Speaker: Auditorium 23, DIY copper.
ACCESSORIES Box Furniture Company D3S rack (source & amplification
components); OMA slate plinth (Thorens turntable); Breyer horse (“Pandora”)
as chassis damper (amplifiers); Keith Monks record-cleaning machine.—Art Dudley
ited (ripped from the “Red Book” CD
layer of Columbia CH 90324) sounded
as I’ve come to expect over the course of
several years: a little bright. (In the opening of “Queen Jane Approximately” in
particular, the trebly electric guitar and
hi-hat tambourine can be a bit much.)
The Nova rounded off those highfrequency edges, and seemed to spread
the left-channel piano and the rightchannel organ farther away from each
other—qualities that it imposed on a
variety of other recordings, as well. The
distinctions were sufficiently slight that
the Nova review sample’s longer run-in
period could well have been a factor; still,
those whose rooms and speakers are more
I n m y room
W
hen I first listened to
the Peachtree iDecco—
in my room, with my
Advent Loudspeakers—
it was like finding the Holy Grail, or
a 10,000-year-old Macedonian ballet
shoe. It was awesome. The sound
was much clearer than with headphones. But this . . . there are no
words for it: The iDecco had spirit. It
almost echoed in my tiny little (no
other words for it) black-hole-ofsound bedroom.
Even with the trickiest pieces of
music—such as Strauss’s Die Fledermaus, from the Twilight soundtrack,
or the Cranberries’ “Linger”—the
iDecco was perfect, accentuating
underlying notes, or subtle crescendos and decrescendos.
And it’s not too steeply priced—
bon appétit and happy shopping!
—Julia Dudley
kind to soft trebles, and whose needs don’t
include an iPod dock, may wish to hold
out for the higher-priced spread.
Conclusions
In the August 2009 Stereophile, John
Marks suggested that Peachtree Audio’s Nova is “the Dynaco Stereo 70 for
the 21st century.” Well said—and if so,
Peachtree’s iDecco is surely the latest
incarnation of the Advent 300 receiver:
great source, great styling, great sound.
The source part is obvious, the styling subjective—and, I’m happy to say, the
sound is wonderful. On the one hand,
the iDecco is much closer than the average affordable product to having what I
consider true perfectionist-quality sound:
very good bandwidth, openness, clarity,
timbral neutrality, and smoothness, with
spatial qualities that, if not quite topdrawer, are surely leagues above those
from which the average Peachtree owner
will have just upgraded. On the other
hand, comparing the iDecco to my own
system of Shindo tube electronics and
vintage phono components—a larger investment by a factor of 30 or so—is silly
to the point of pointlessness: To paraphrase Voltaire, the better may indeed be
the enemy of the good, but for the vast,
hurtling majority of people, the iDecco
is the better.
And even for this perfectionist, it’s
quite good enough: During its time in
my home, the Peachtree iDecco proved
so delightful, so indispensable, that I
had no choice but to buy it. A perfectionist-quality music system—just add
speakers!—with a three-figure price? For
the domestic audio market of 2010 and
beyond, a more important new product
is hard to imagine.
nn
Posted with permission from the December 2010 issue of Stereophile ® www.stereophile.com. Copyright 2010 Source Interlink Media. All rights reserved.
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