Digital Processor Reviews

In its ability to clarify individual lines and, especially, to make sense of a rhythmically dense orchestration, all while maintaining very good tone and scale, the iDAC sounded magnificent with a JVC transfer of Fritz Reiner and the Chicago Symphony Orchestra's classic recording of Bartók's Concerto for Orchestra (ripped from JMCXR-0007). It was more spatially convincing than the DragonFly—and, remarkably, than my LP of this recording (admittedly, a second-rate Victrola reissue). My listening notes include a surprisingly coherent reference to my astonishment.

The iDAC also turned in an all-around fine level of performance with piano music. It brought not only clarity but well-balanced tone and excellent timing precision to a live performance by Mieczyslaw Horszowski of Chopin's Waltz in C-sharp Minor, Op.64 No.2 (ripped from an out-of-print BBC Legends disc, BBCL 4122-2), respecting well the manner in which Horszowski's light touch gives an ironic counterpoint to the work's gravity. The iDAC allowed even greater clarity and poise, and a commendable lack of stress, to John Atkinson's 24/88.2 WAV file of Robert Silverman performing the Theme and Variations 1–5 of Beethoven's Variations on a Waltz by Diabelli—a drier recording than the Horszowski, and one in which natural texture, especially evident in note decays, was very well preserved. (One hears still more piano tone and texture through the best analog, I think, but this listening experience was thoroughly satisfying.) The iDAC was also more than capable of highlighting the considerable sonic and musical distinctions between the above hi-rez file and the pleasant but overly rounded and comparatively flat-sounding CD edition of JA's recording (Variations, Stereophile STPH017-2).

Compared to the iDAC, my own Wavelength Proton USB DAC—itself both a breakthrough and a bargain at the time of its introduction—seemed very slightly flat, especially in terms of texture and impact. The Proton did, however, have a somewhat richer timbral balance overall, which I continue to prefer through my system, especially with Altec Valencias in place of my Audio Note Type E speakers. That distinction became even more apparent when I compared the two DACs through their headphone amps, using the Sennheiser PMX 90s I borrowed from my daughter. (I dislike listening through headphones, relying on them only when the cold, oily gun of reader expectations is pressed against my temple.)

Power by iUSB
Inserting the iUSBPower between my computer and the iDAC produced various and subtle changes. With Gillian Welch's remarkable "Dark Turn of Mind," from her The Harrow & the Harvest (ripped from CD, Acony ACNY 1109), the reportedly cleaner power supply produced a clearer sense of force in the note attacks of both Welch's and partner David Rawlings's guitars, and a better, clearer spatial presence to her voice, all without apparent penalty. To hear how the iUSBPower might affect music of wider bandwidth, I turned to that favorite chestnut, Led Zeppelin's wonderful "Since I've Been Loving You," from the fancifully titled III (ripped from CD, Atlantic A2-19128), and listened appreciatively as the iUSBPower allowed greater depth and power to the wonderfully big, undamped sound of John Bonham's bass drum—and, at the other end of the spectrum, imparted greater clarity and insight to the words Robert Plant sings as well as Jimmy Page's softer guitar noodlings.

By now, during an evening of listening with greater concentration (read: stress) than usual, I could also hear a slight—an exceedingly slight—difference between the iUSBPower's two ground-switch settings. I preferred the sound with the ground unlifted, in which case the music sounded slightly bigger overall. If that's an example of a positive response to a subtle undercurrent of noise and distortion . . . well, so be it.

Conclusions
The iFi Audio iDAC performed without flaw, playing music files with exceptional clarity, a natural-sounding tonal balance, and fine color and texture. It was detailed and pleasantly dramatic and forceful, the latter qualities serving not only the high-resolution examples described above, but bog-standard MP3s, too—as when streaming music from my new favorite Internet radio station, WCKR, of New York's Columbia University. (Their Sunday-morning bluegrass hour, The Moonshine Show, is a delight.)

For my money, the Halide DAC HD ($495) is still the USB DAC to beat for $500 (footnote 3) and under, given its excellent musicality and its surprisingly rich, colorful, well-textured sound. The AudioQuest DragonFly ($250), while sounding less rich and complex with hi-rez music files, is more than deserving of comparison and remains a superb value, especially when one considers its American provenance. The iFi iDAC, although a little more expensive, is also a little more sophisticated and satisfying. I'm not sure that the addition of the iUSBPower external power supply brings the iDAC all the way into Halide territory—or, for that matter, whether the added expense represents as good a value as the iDAC itself—but the answers to those questions may become clearer when iFi Audio introduces the iUSBPower-specific cabling options they've planned for later this year.

In the meantime, even as computer-audio products become more commonplace, some of us continue to cheer the action at this more affordable end of the market: The bloom may be off the DAC rose, but the options available to the audiophile on a budget seem to get sweeter every year. Highly recommended.

Further observations
Editor's Note: When they received the preprint of this review, Abbingdon Music Research were concerned that our review sample, one of a batch shipped to the US in time for last October's 2012 Rocky Mountain Audio Fest, was faulty. In particular, they felt that the measurements indicated a problem with the D/A chip, which directly drives the line output. They asked if they could submit a sample from current production for Art Dudley to compare with the original and for me to measure. Art's comments appear below; my comments on the revised sample can be found in the "Measurements" sidebar of this review.—John Atkinson

Upon the return from JA's test bench of the original review samples of the iDAC and the snappily named iUSBPower, I began by connecting the iDAC directly to my computer; in the Sound subwindow of my iMac's System Preferences menu, the AMR-made D/A was correctly identified as "AMR USB Audio 2.0." Later that evening, I added the original iUSBPower to the system. At first, the computer reaffirmed its recognition of the iDAC. I powered down the computer at bedtime, but left the iDAC and iUSBPower connected, the latter with its wall wart still plugged in. The next morning, when I powered the computer back up, it did not find/recognize the iFi gear at all. I broke and remade the USB connection several times in succession; on the fifth try, the computer recognized the iDAC.

Later that day, I again connected to my computer the new review sample of the iDAC; my computer recognized it. I added the new sample of the iUSBPower; my computer again recognized the iDAC and identified it correctly. I left both iFi units connected, then did a hard reboot of my computer. But when I powered it back up, my computer couldn't find the iDAC—just as with the original samples. This time, I had to break and remake the USB connection only once: The iDAC was located and correctly identified on the second try (footnote 4).

With Ella Fitzgerald and Louis Armstrong's performance of "Moonlight in Vermont," from Ella and Louis (HDtracks download, Verve), my original review sample of the iDAC and the one newly supplied by AMR sounded almost identical, with the same degree of detail resolution, precisely the same image placement and stereo stage depth, the same "noise character" (ie, neither was more or less grainy than the other), and the same timbral character overall.

Yet there was an exceedingly subtle difference, one that showed up only after multiple listenings: Through the new sample, the lowest notes of the double bass seemed very slightly deeper and more powerful than through the old—which, of course, one may take to be a good thing. But allied to that quality, the new sample also had a very slightly more prominent upper treble: The voices (and trumpet solos) on this record are notoriously upfront and stark, with just a tad too much sibilance through most systems, yet the newer sample of the iDAC seemed ever-so-slightly more sibilant.

Again, I must stress that these differences were at the very threshold of audibility. And, as they became apparent, I found myself wondering about a simple explanation for them: Both qualities, taken together, could be the result of a minutely higher output level in the new sample (footnote 5).

I heard precisely the same differences, just as subtly, with "Moonlight Midnight," by Peter Rowan and Tony Rice from Quartet (CD/AIFF, Rounder 610579). Again, it seemed to me that the new sample of the iDAC had marginally more gain than the original; the result was that, with the system volume optimized for the older sample, swapping in the new one made for sound that was very slightly unpleasant—very slightly "hi-fi"—by comparison.

Overall, my final thoughts, expressed in the next to the last paragraph of my conclusion, endure: Though I recommend the iFi iDAC, the Halide HD DAC is still better (richer, more colorful, more present, and more tactile) than the iDAC, with or without the iUSBPower.—Art Dudley

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Footnote 3: That's a slightly unfair number to use as the basis for comparison, since the Halide incorporates its own USB cable and converter-to-preamp interconnect.

Footnote 4: I found that whether or not the iDAC would be consistently recognized by the host computer could be affected by wiggling the AMR-supplied USB link in the iUSBPower jack, where it was a slightly loose fit.—John Atkinson

Footnote 5: The measured maximum output level at 1kHz of the second iDAC sample was just 0.035dB higher than that of the original; the MOL of the sample reviewed by Michael Lavorgna was slightly higher than that.—John Atkinson