December, 2012
Audio Research
DSPre Preamplifier-DAC
AudioQuest’s tiny new DragonFly, which combines a D/A converter and
headphone/line amplifier in a chassis no larger than a USB flash drive, illustrates
that a good DAC doesn’t require a full-width chassis or anything near that size.
A DAC can be built into a line stage, to produce a single-box component to which
all source components, digital and analog, could be connected. That single box
would save a shelf on your rack, and you could use its single remote control to
select among all of your sources. But perhaps the most appealing feature
of a combination DAC/line stage is lower cost. You need only one chassis, one
remote, one power supply, and no interconnects between DAC and line stage.
The only drawback to such a combination would be if you wanted to upgrade
your DAC or line stage; you’d have no choice but to upgrade both. (Although I
suspect some of you reading this would regard that as an advantage.)
Apparently, someone at Audio Research Corporation had the same vision, and
designed the DSPre ($7495 USD), which includes not only digital circuitry derived
from ARC’s DAC8, but a full-function line stage — all in a chassis scarcely larger than
that of their LS27 line stage, which is 0.7” shallower. The DSPre measures 19”W x
5.75”H x 14”D, and the two models weigh exactly the same: 13.2 pounds.
What has Audio Research given up to squeeze all that functionality into the DSPre?
Tubes. The DSPre, like the DAC8, uses nothing but JFETs in its circuits, and it has one
of the sweetest-sounding output stages I’ve heard. So rather than build a sweet output
stage for a line stage and another for a DAC, ARC elected to combine the two in a
single space-saving chassis. And you won’t have any tubes to replace — ever.
"The DSPre did full justice
to ARC’s reputation
for superb sound,
and did so
without using tubes."
The DSPre looks just like any other Audio Research line stage: On a faceplate in black
(the review unit) or silver, two large, oval knobs flank a large digital display that shows
the DSPre’s current status. The two knobs don’t rotate freely; turning them left or right
starts the control moving in that direction. The left knob is a 104-step volume control;
the right, the input selector. Above the display is a label that reads “Definition Series,”
which is how ARC denotes their all-solid-state models. Below the display is a row of
seven pushbuttons: Power, Sample, Menu, Enter, Mono, Invert, and Mute.
On the rear panel are lots of jacks. Still, unlike ARC’s more advanced (and expensive)
line stages, the DSPre doesn’t have both XLR and RCA jacks for each and every input
and output; rather, it has two XLR inputs, one XLR output, three RCA inputs, and one
RCA output. Also, since this is a DAC and a line stage, there are five digital inputs:
high-speed USB 2.0, AES/EBU, RCA, BNC, and TosLink — all capable of playing files of
resolutions up to 24-bit/192kHz. A driver is supplied to enable Windows computers to
operate at 24/176.4 and 24/192 through the USB input. There is a set of unbalanced
Record Out jacks for those who wish to make recordings from the DSPre. There are
input and output jacks for 12V in/out remote trigger signals, and an RS-232 connector
lets you connect the DSPre to a whole-house remote-control system like the Crestron.
And, of course, there’s an IEC connector for the power cord. Like all ARC gear, the
DSPre’s cord was chosen for its sonic qualities, so don’t toss it in the drawer; you may
be surprised at how good it sounds.
With all the functions (and then some) of the DAC8 and LS17SE line stage, the DSPre
has by far the most complex remote control I’ve seen from ARC. It’s no more complex
than the average Blu-ray player, but it does have to control both digital and analog
functions, which requires lots of buttons.
It was interesting to compare the DSPre with other Audio Research components: at a
digital input level of 0.0dB, the DSPre puts out 15V RMS compared with the DAC8’s 6.4V,
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which means that the DSPre has more headroom and greater dynamic range (117dB).
Also, the DSPre’s discrete analog bandwidth is greater than 200kHz, while for the
DAC8 it’s greater than 90kHz, and for the DAC7, 35kHz. The DSPre’s signal/noise
ratio is specified as 120dB: incredibly quiet. It’s always a good idea to pay attention
to a device’s input and output impedances, to ensure compatibility with source
components and power amplifiers; the impedances of the DSPre’s analog inputs are
120k ohms (balanced) and 60k ohms (single-ended). The digital inputs are at the
standard impedances of 75 ohms (S/PDIF) and 110 ohms (AES/EBU). The output
impedances are 500 ohms (balanced) and 250 ohms (single-ended). The DSPre
should not be used to drive a load lower than 20k ohms or higher than 2000pF
maximum capacitance.
You can use the Sample button to upsample on S/PDIF via hardware. If you want to
upsample on the USB input, you’ll need to use external computer software, which is
plentiful. Through the USB input, the sampling-rate-conversion receiver is bypassed,
to maintain very low master-clock jitter. Use the Menu button to access labels for the
various inputs, and Enter to select a name. All of these functions, and more, are also
present on the remote control.
The DSPre is warranted for three years, parts and labor — in my view, an appropriate
warranty for a high-end component at this price. My experience has been that Audio
Research’s warranty service is fast, thoroughly competent, and very supportive.
"It’s often suggested
that it takes tubes
to do justice to
the spatial aspects of
a recording, but the
DSPre proved
it ain’t so."
Setup and use
I removed my Audio Research LS27 line stage from my equipment rack to make room
for the DSPre. Since the DSPre is only slightly deeper than the LS27, it easily fit on
the shelf. I rerouted the Wireworld Gold Starlight 6 S/PDIF cable and Wireworld Gold
Starlight 5 AES/EBU input cables from my digital sources (a server and a CD transport)
to feed the DSPre’s digital inputs instead of my ARC DAC8. I connected the DSPre’s
output to my ARC VS115 power amplifier using Clarity Cables’ Organic balanced
interconnects, and used the DSPre’s stock power cord.
I installed ARC’s latest Windows USB driver on my laptop computer so I could
play music via the DSPre’s USB input. The DSPre uses the same Windows USB
driver as the DAC8. A new, more flexible driver, available for download from
www.audioresearch.com/downloads.html, supports Kernel Streaming and Windows
Audio Session API (WASAPI); a new version of the ASIO driver is also provided. USB
drivers are also needed for Apple computers. ARC has yet to offer any drivers for Linux.
ARC recommends 600 hours of burn-in, so I put the server on repeat and let it play
that long. Of course, sometimes I took the server off repeat to listen to some music.
Then I burned in the USB input for another 200 hours. In my experience, you need
to burn in a component with a signal, as opposed to just turning the component on,
and the USB input uses a separate circuit board that doesn’t receive a signal unless
a USB source is connected.
You can name the DSPre’s inputs to show which source component is connected to
each. For example, if you don’t like to see your S/PDIF input described as “RCA,” you
can name it “CD.” The Menu button on the remote takes you to the input-naming
menu, where you can scroll through an assortment of source names and select the
one you want to assign to a particular input.
You can use a dedicated, standalone server like my Auraliti PK100, but many listeners
use computers running the appropriate software as servers, and that means using the
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DSPre’s USB input. To evaluate how the DSPre sounded with a computer as source,
I used JRiver’s Media Center running on my laptop, with playback controlled from
my iPad via the JRemote app. An AudioQuest Diamond USB cable connected my
computer to the DSPre.
Sound
My initial impression of the DSPre was that its soundstage was huge. On Craig Hella
Johnson and Conspirare’s Requiem (24/88.2 FLAC, Harmonia Mundi/HDtracks), both
the spaciousness of the room and the locations of individual choirs in that room were
clearly defined. It’s often suggested that it takes tubes to do justice to the spatial
aspects of a recording, but the DSPre proved it ain’t so. Requiem also demonstrated
the DSPre’s finesse with dynamics. As the music quickly crescendoed from a soft
pianissimo to a powerful climax, the DSPre showed how much power a choir
can generate.
"It sounded fantastic,
looked great,
and was easy to use.
Equally important,
it would save space
and money
over separate
components."
Bass was fairly deep, with lots of impact. In J.S. Bach’s Prelude in D, performed by
organist Virgil Fox on Reference Recordings’ 30th Anniversary Sampler (16/44.1 FLAC,
Reference Recordings), the bass went deep with plenty of weight, even though my
subwoofers were disconnected. (The DSPre won’t drive my JL Audio Fathom f110
subs’ low input impedance of 10k ohms.)
Although extended, the highs were not at all peaky. On Praetorius: Dances from
Terpsichore & More (16/44.1 FLAC, Alto), with the Praetorius Consort led by
Christopher Ball, the chimes rang out with unusual detail and clarity. However, the
DSPre added no extra high-frequency energy, as is sometimes the case with solid-state
gear, and the detailed treble information was not even slightly threadbare. The DSPre
clearly depicted the initial strike of the mallet, the full harmonics of the sustain, and
the decay of the notes as they wafted their way to silence.
In Custer LaRue’s Ballads (16/44.1 FLAC, Dorian), the soprano’s voice floats ethereally
in front of a harpist and flutist from the Baltimore Consort, an early-music group.
The DSPre brought out how much like a real person singing this recording sounds;
LaRue enunciates words with a clarity I’ve seldom heard. My favorite track is “Gloomy
Winter’s Now Awa’.” Despite the fact that LaRue sings in an old Scotch dialect, I
can almost understand the words, which is remarkable. I’m a big fan of old Scotch,
especially that from Glenmorangie.
Beat Kaestli is a Swiss jazz singer whose album Invitation (24/88.2 FLAC, Chesky/
HDtracks) includes his interpretations of several standards. I particularly liked his cover
of Johnny Mercer’s “Day In, Day Out,” which features subtle modulations of vocal
tone and pitch, along with microchanges in tempo. The accompanying combo, too,
was well recorded. The DSPre presented the music with amazing clarity, making the
recording’s hi-rez origin quite clear. Kaestli’s vocal modulations were extremely well
defined, giving the reproduction of his voice considerable realism. In other words, the
DSPre made this recording sound remarkably like someone singing.
Czech composer Antonín Dvořák’s music is chock-full of delightful tunes, as clearly
highlighted in Iván Fischer and the Budapest Festival Orchestra’s recording of his
Symphony No.7 and Suite in A Major (24/192 FLAC, Channel Classics). The DSPre
precisely portrayed the harmonic envelopes of the orchestral instruments. It also gave
the orchestra plenty of midbass weight, just as you’d hear in a live performance. The
burnished glow of the orchestral strings filled the room.
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All of my listening impressions so far were gathered while using, as the source, my
Auraliti PK100 music server, which has an S/PDIF output. How did the DSPre’s USB
input sound? Without going through a song-by-song comparison, I’ll just say that
I found that music via the USB input demonstrated better-defined timbres with
increased harmonic density, so that instruments sounded just a smidgen more
realistic. Spatially, the USB input seemed to pinpoint performers in space very slightly
more precisely than the S/PDIF input. I thought there was also just a bit more treble
extension via the USB input, though nothing edgy or peaky.
These findings shouldn’t be used to fuel the USB-vs.-S/PDIF debate: Several factors
besides the input were at play. For example, the cables I used to connect the S/PDIF
and USB sources to the DSPre are from different manufacturers: the USB cable is a
top-of-the-line model, while the S/PDIF cable is a midline cable. Likewise, I use JRiver
Media Center software on my computer, but Music Player Daemon software in my
Auraliti’s dedicated Linux server; JRiver may be more sophisticated. All I can say is that
in my system, with the cables and different sources I used, I very slightly preferred the
USB input to the S/PDIF. This was exactly the difference I heard when reviewing the
DAC8: its USB input sounded slightly better than its S/PDIF. Don’t just take my word
for it; ARC thinks the USB inputs sound better, too.
Comparison
I replaced the DSPre with my LS27 line stage and DAC8. Although this combination
sells for $11,990, it represents a choice between two likely front-ends from Audio
Research. The DAC8-LS27 combo has additional costs: 1) a shelf on my equipment
rack that I could use for another piece of equipment, and 2) interconnects from DAC
to line stage. I used Audience balanced Au24 e interconnects to link the DAC8 to
the LS27.
The DSPre’s display is easier to read than the DAC8’s. Where the DAC8 shows you the
sampling rate of an incoming bitstream by using a status light for each of the common rates, the DSPre displays the words “96 Native” to indicate that 96kHz is the
recording’s original sampling rate, and is not the result of oversampling.
Associated Equipment Speakers —
Affirm Audio Lumination speakers,
JL Audio Fathom f110 subwoofers
Amplifier —
Audio Research VS115 stereo amplifier
Preamplifier —
Audio Research LS27 line stage
Digital sources —
Hewlett-Packard dv7-3188cl laptop
computer running 64-bit
Windows 7 Home Premium,
foobar2000 version 1.1.5, and
JRiver Media Center;
Auraliti PK100 music server;
all servers and digital players connected
to an Audio Research DAC8
Interconnects —
Clarity Cables Organic,
Audience Au24 e
Speaker cables —
Clarity Cables Organic
Power cords —
Purist Audio Design Venustas,
Clarity Cables Vortex,
Audience powerChord e
Digital cables —
Wireworld Gold Starlight 6 S/PDIF,
AudioQuest Diamond USB
Compared to the DSPre’s best-sounding input, the USB, the soundstage of Conspirare’s
Requiem was just as huge through the DAC8-LS27 combo, but the sense of depth
was a bit better defined. I don’t mean I could precisely estimate how far from the rear
wall of the recording venue each singer stood — I haven’t been able to do that with
any component — but there was definitely more of a sensation that there was depth
within the choir itself. Also, the sound of the choir had more texture and detail, and
more of a sense of individual singers. The difference was quite small, but noticeable.
The chimes on the Praetorius album were certainly audible, but more extended
through the DSPre. The DAC8-LS27 made it a bit more obvious that the flute in Custer
LaRue’s Ballads was a wooden flute, not a modern metal flute; it sounded breathier,
though no less agile in the hands of expert flutist Chris Norman. Beat Kaestli sounded
a little more robust, with stronger chest tones. His instrumental accompaniment
sounded just as detailed through the DAC8-LS27 combo.
Without the high-frequency extension of the DSPre, the tonal balance of Dvořák’s
Symphony No.7 was focused a little lower in the audioband — the strings sounded
just a tad richer. Obviously, the differences in high-frequency extension between the
two systems favored the DSPre — but don’t forget that an extra set of interconnects
was involved, which may have affected this aspect of the sound.
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Bottom line
I’m betting that Audio Research’s DSPre preamplifier-DAC is an early example of a
component we’ll see more of in the future: a single box into which can be plugged
cables from all sources, digital and analog, and whose switching capabilities will let
you choose any of those sources using a single remote control. It just makes too
much sense.
All of those advantages would be moot if the DSPre sounded mediocre, but I doubt
ARC could make a mediocre-sounding component if they tried. The DSPre did full
justice to ARC’s reputation for superb sound, and did so without using tubes. It
sounded fantastic, looked great, and was easy to use. Equally important, it would
save space and money over separate components. If I didn’t need a separate DAC
and line stage to pursue my reviewer’s craft, I’d gladly live with the ARC DSPre. Easily
a Reviewers’ Choice.
Audio Research
DSPre Preamplifier-DAC
Price: $7495 USD.
Warranty: Three years parts and labor.
Audio Research Corporation
3900 Annapolis Lane N.
Plymouth, MN 55447-5447
Phone: (763) 577-9700
Fax: (763) 577-0323
Website: www.audioresearch.com
. . . Vade Forrester
[email protected]
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