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- Written by Vade Forrester Vade Forrester
- Category: Full-Length Equipment Reviews Full-Length Equipment Reviews
- Created: 01 December 2012 01 December 2012
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 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, 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 warrantied 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.
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 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.
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.
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.
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.
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.
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.
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.
. . . Vade Forrester
- 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
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