Digital Processor Reviews

Robert Deutsch, September 1992 (Vol.15 No.9)

It was on the third day of the Los Angeles Stereophile High End Hi-Fi Show that I finally had a chance to have lunch with Bob Harley and get the inside scoop on the latest "hot" digital gear.

"So, I hear you've been listening to the PS UltraLink. How is it?"

Bob chewed thoughtfully on his hamburger.

"It's really good. Not as good as the Mark Levinson No.30, but really good."

Now, from anyone else, that may sound like faint praise, but you have to keep in mind that RH is not one to make pronouncements of the "All Else Is Gaslight" (or "All Else Is Boat Anchors") type, and he's evaluated just about every D/A processor on the planet. The $14,000 Mark Levinson No.30 is his personal reference, the best he's heard. For the vast majority of audiophiles, myself included, purchase of a $14,000 D/A processor is simply out of the question, but $2000 is a distinct possibility. I just had to check it out in my system. As it turned out, one of the UltraLink review samples was being used at the High End Show, so, with JA's approval, I took it home after the end of the Show for a "Follow-Up."

Whereas Bob's approach in evaluating the UltraLink was primarily to assess how close it comes to the cost-no-object best, my concern was whether—and to what extent—it's superior to the very good. I had two D/A processors around that are certainly in the "very good" category: the Proceed PDP 2 (Class B in April's "Recommended Components") and my own Aragon D2A, updated to Mk.II status. Transport was the Proceed PDT 2; connection between the transport and the D/A processors was via coaxial cable (MAS MASterLink, AudioQuest Digital Pro, and TARA Labs Digital Master), except in the case of the PDP 2, where it was the preferred balanced XLR (AudioQuest Diamond). This sample of the UltraLink was without the optional AT&T ST glass-fiber input, which didn't bother me, since I didn't have access to a transport with an ST output anyway. The rest of the system consisted of my usual bi-amped "stripped" original Quads, driven by a Luxman MQ 68c, and Cizek MG-27 subs driven by a Bryston 3B, via a Dahlquist LP-1 crossover. The listening room is supplied with two dedicated AC lines; all the electronics are plugged into a Tice Power Block. Some of the comparisons were done with the Stax Lambda Signature/SRM-T1 headphone combination. Preamplifier was the Perfectionist Audio CPR IIIb/TIPS (review forthcoming).

Back in the early days of digital, before I even owned a CD player, I bought my first CD: the Original Broadway Cast recording of 42nd Street (RCD1-3891). This was my Test Piece: I used it in audio stores and at home to evaluate CD players. I finally took the plunge with the Mission 7000R, which was just good enough to show the promise of the new medium. Digital reproduction has improved a lot since then, and although I retain a fondness for analog, I now listen to CDs more than LPs, and am committed to extracting all the music I can from those bumps and pits. Whenever I evaluate a new digital product or tweak, sooner or later 42nd Street finds its way to the CD player/transport, with the result that I've heard this CD more than any other in my collection. With the UltraLink installed in my system and having warmed up for a couple of days, it was time to play a CD. Whaddaya know—42nd Street is already in the transport! Set the volume at a moderate level, and press Play.

Wow! Did someone substitute a newly remastered "audiophile" version of my nearly decade-old CD? Where did all that space come from? And what happened to the trumpets' rough, raspy edge that I thought was part of the recording? Now they sound more like...trumpets. And when the chorus starts tap-dancing their way across the stage, the taps are clearly in the foreground, with the orchestra laid out behind them. Each tap has a crisper, more distinct sound than I remember hearing on this record.

Wait—let's not jump to conclusions. Perhaps I'm just in an unusually receptive/positive mood. Change over to the Proceed PDP 2. Play the opening of 42nd Street again. Hmmm. Not bad. Pretty good, actually. But there's that slightly raspy, grainy quality; the sense of instruments existing in space is not as convincing; I'm more aware of the artificial nature of the reproduction process. Back to the UltraLink. Aah. I was right. The highs are more delicate, less overladen with electronic (digital?) garbage; everything just sounds more real.

Over a period of several weeks, these initial positive impressions of the UltraLink were confirmed with a variety of recordings. The percussion solo on the new Stereophile Test CD 2 was reproduced with explosive transients, and with an exceptional sense of the ambience of the recording venue. I'm not a fan of synthesizers or the use of highly processed recordings to evaluate audio equipment, but I have to admit that even Corey Greenberg's "Eden" (a deliberately synthetic recording) sounded cleaner and more open with the UltraLink than with the Proceed PDP 2.

For me, the most important attribute of the UltraLink is its ability to reduce the sense of strain and congestion while unraveling complex musical passages involving orchestra, chorus, and soloists. The first ten minutes of Puccini's Turandot has everything-but-the-kitchen-sink orchestration, and a stage full of people singing their hearts out. It's exciting music, but the CD of the Mehta recording (London 414 274-2) can sound like a bit of a mess if any part of the reproduction chain is not up to the challenge. For this comparison, I used the Stax Lambda Signature/SRM-T1, switching between the Proceed, Aragon, and the UltraLink. Results: a clear victory for the UltraLink. I could hear more of the musical information on the recording, without any added hardness or a fatiguing, overly detailed quality. The D2A Mk.II was in second place, with dynamics that were actually a close match for the UltraLink, but the UltraLink had more of a "see-through" quality, with a more three-dimensional ("palpable," if you like) rendering of voices and instruments, and a more realistic sense of ambience.

In what was overall a rave review of the UltraLink (see Vol.15 No.6), Bob Harley made one comment that gave me some concern: he described it as having a slight forwardness in the midrange. Now, I should explain that, like RH, I'm a laid-back kind of guy, and while I want the sonic perspective to be as neutral as possible (who doesn't?), if forced to choose, I'll take a laid-back sound over one that's on the forward side. In listening to the UltraLink, I paid particular attention to any indications of an unduly forward presentation. I have to agree with RH that the UltraLink does present a somewhat up-front image, but the effect in my system is very slight. With levels at 1kHz carefully matched, the UltraLink placed John Wustman's piano and Pavarotti's voice (you were thinking maybe sousaphone?) on Pavarotti at Carnegie Hall (London 421 526-2) a couple of feet closer to the listener than the Aragon D2A Mk.II, but the spatial relationship between piano and voice was well-maintained.

The UltraLink also had no difficulty with the depth of image test on the second Chesky Test CD (JD68); the clicker receded into the distance just as the announcements say it should. Dipoles like the Quads (mine have had the absorbent material removed from the rear) have greater built-in depth than forward-firing speakers like Bob Harley's Hales System Two Signatures; coupling the Quads with the zero-feedback Luxman tube amp produces a very laid-back sound, so that a forward tendency in associated equipment is not as likely to be bothersome. The best way to evaluate the match between an audio system and any new component is always a home trial, but my guess is that the system as a whole would have to sound forward in the extreme for the UltraLink's tonal balance to present a problem.

Power cables. Digital cables. Yoicks! It's bad enough that interconnects and speaker cables make a difference—unless, of course, you belong to the far right of the AES—but it now appears that the conduits for the humble AC and for the digital ones and zeros can also influence the sound. PS Audio's Randy Patton told me that the UltraLink is quite sensitive to these associated wire components; in fact, the UltraLink is now supplied with a heavier-gauge power cable than the original Stereophile review samples. He provided me with one of the new power cables and suggested that I might find even better results with the TARA Labs Affinity AC cable. I tried the TARA Labs AC cable and found that it did allow the UltraLink to sound a little more transparent, but the effect was fairly small (footnote 1).

Plugging both the transport's and the D/A processor's AC cables into a Perfectionist Audio IDOS power bar (the outlets marked "digital," of course) proved to be of greater benefit, with an increase in the size of the soundstage and better focus on individual instruments. The Perfectionist Audio DIF, which provides a separate ground for the output of the D/A processor, didn't do much for the UltraLink; if anything, the sound was softened too much (footnote 2).

I also tried several digital cables: AudioQuest's Digital Pro was very good, but the new TARA Labs Digital Master, a cable that retails at (gulp!) $595 for a 1m length, was even better, providing a clearer vision into the soundstage. The UltraLink can be equipped with an optical ST input for $200, and glass-fiber cables are only about $100, so, for those who own or have plans to get a transport that has an ST output, going the ST glass-fiber route would be a better, more cost-effective approach. (The consensus seems to be that the ST connection is superior to any coax.) $595 is an awful lot to pay for a short piece of wire, but it does deliver the goods (footnote 3).

Anyone familiar with the ever-changing world of digital technology knows that buying an expensive D/A processor is not the safest investment one could make. But what does "expensive" mean? What's a reasonable amount to pay for a D/A processor? The answers to these questions obviously depend on the state of one's finances as well as the value one places on what are, to the average person, fairly subtle aspects of sound quality. The UltraLink's $2000 cost puts it at the top of the range of "reasonably priced" processors, but well below the cost-no-object group. Would you get your money's worth if you bought the UltraLink? It is, by a considerable margin, the lowest-priced processor to use the expensive UltraAnalog DAC, and there's no evidence of corner-cutting anywhere else in its design. More to the point, it sounds significantly better than even generally well-regarded D/A processors like the Proceed PDP 2 and the Aragon D2A Mk.II. Is it the best D/A processor you could buy for $2000?

I don't know. New and/or improved D/A processors are being introduced at an alarming rate, and even if it were possible to survey all contenders, the survey would be obsolete by the time it appeared in print. There's certainly something to be said for waiting until the dust settles. But when will it settle? Will it ever settle?

Enough waffling. The UltraLink sounds so good and offers such conspicuous value among high-end D/A processors that, as much as any digital equipment can be said to be a safe buy, this has to be it. The ST glass-fiber connection is retrofittable, and PS Audio has a commitment to making upgrades available at reasonable cost; even if, say, UltraAnalog comes out with an improved version of their DAC, UltraLink owners won't be left behind. I'm buying the review sample.—Robert Deutsch

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Footnote 1: I also replaced my Quads' home-made 14-gauge AC cables with a set of TARA Labs cables: a very significant improvement, highly recommended for Quad owners.

Footnote 2: The Aragon D2A Mk.II, on the other hand, sounded better with the DIF.

Footnote 3: Sam Tellig, a man of Cheapskate origins, has touted the benefits of the $495 Goldmund digital cable (see Vol.15 No.6), and Jack English is keen on the NBS cable, which retails at $800! Where will this madness end?