The Fifth Element

For real-world purposes, that 6/2.88MHz signal can be thought of as "quasi-DSD" or "pseudo-DSD"—or perhaps just "DSD." For all the faith-based on-line chatter about DSD being a 1-bit system, as a practical reality, DSD converters usually handle data in 4–6-bit chunks; only the earliest generation (ie, early 1990s) of delta-sigma converters used 1-bit architecture. Modern modulators are usually 4- to 6-bit, because the signal/noise ratio of a 1-bit converter is just 6dB, mandating use of high-order noiseshaping with such a converter, which increases the level of noise above the audioband.

One might wonder if, had the people at Sony known in the late '90s what we know now, they might have built a blindingly fast 6-bit system instead of a blindingly fast 1-bit system. That leaves aside the issues of DSD's high levels of noise outside the audioband, and the consequent necessity of filtering the output so that, in playback, DSD's usable bandwidth is closer to 47kHz (or perhaps even 30kHz) than to 100kHz.

Michael Grace has a droll sense of humor. The most memorable quip in our wide-ranging conversation was his observation that adding DSD capability to a Grace Design product is more a matter of making it "history-proof" than "future-proof." After all, commercial DSD encoding has been kicking around since the launch of SACD in 1999.

The m905's asynchronous USB interface is based on XMOS's digital interface chip, whose stock code Grace Design spent more than a year tweaking. Michael Grace: "The XMOS chip receives data from the USB bus in PCM form and hands it off to the DAC chip. In the case of DSD, the DoP standard (DSD over PCM) allows DSD data to be 'packed' into a 176.4kHz PCM stream. That way, the computer 'thinks' it's sending PCM audio, which is included in the USB Audio Class Specification. The XMOS chip 'unpacks' the DSD data from the PCM frames and sends it on to the DAC in DSD form."

Grace Design provides online support; the m905's firmware is updatable by download and then USB connection to the remote control.

Sound Quality
The essential sound of Grace Design's m905 was, in a word, magnificent. Even 16/44.1 CDs came across with an added sense of realism. The first lute notes of Joel Frederiksen and the Ensemble Phoenix Munich's Requiem for a Pink Moon (CD, Harmonia Mundi HMC 902111) made my friend Steve Martorella, a very experienced musician, catch his breath. High-resolution material—especially December 2013's "Recordings of the Month," the Grateful Dead's Original 13 Studio Albums in 24/192 Plangent Processes remasterings—was electrifying. "Box of Rain," in particular, was deeply moving. (Phil Lesh co-wrote the song during his father's final illness.)

However, as impressive as hi-rez files were, I did nearly all of my listening to the m905 with conventional CDs, because that's where the largest number of the greatest treasures of digitized music are stored. In addition to Parasound's exceptional Halo CD 1, the other constants in the system were a 2m length of Nordost Silver Shadow S/PDIF cable, Cardas Clear speaker cables and balanced interconnects, and a Lindell AMPX class-A power amplifier. Loudspeakers varied among ATC's SCM7 and SCM19 (to be covered in a future column), and, on loan from an LP-collecting friend, a pair of early-1990s Spendor LS3/5As (11 ohms) in non-original ebony cabinets repurposed from a pair of Rogers LS3/As.

Two comparisons immediately leapt to mind. The arrival of the m905 overlapped by a few days the end of the Bricasti Design M1 DAC's ($9000) tenure here, before the latter went back to the factory to be upgraded with remote control, USB, and DSD capabilities, to be then sent on to John Atkinson for remeasurement. Playing such favorites such as Ella Fitzgerald's recording of Cole Porter's "Easy to Love," from The Cole Porter Songbook, Volume Two (CD, Verve 821 990-2), I expected a more pronounced difference than I heard, given the $5505 difference in price. The Grace m905 and Bricasti M1 sounded surprisingly similar.

The m905's and Bricasti M1's reproductions of musical phenomena—the timbres and dynamics of the notes played or sung—were very close. However, the Bricasti did better at retrieving musical epiphenomena—the small, incidental sounds of instrumental or vocal production, and the subtle, complex clues that can indicate the size and character of the recording venue.

The other comparison was with Grace's own m903 ($1995), long a favorite of mine. I'd recently borrowed an m903 to remind me of its sound, so the aural memories I was relying on were in this case just a few months old. I was taken aback at how much better the m905 sounded—and the m903 does not sound at all shabby. Indeed, when it won Stereophile's Headphone Product of the Year award for 2012, it received nothing but first-place votes. However, the m903 was designed and built to a more stringent budget than was the m905.

In my coverage of the m903 in the December 2011 issue, I noted that a friend who is an experienced listener said that it handled music so gently that it was the first DAC he'd heard that he'd be tempted to describe as "feminine." Another word might be "sweet." I didn't have that impression of the m905—not that the m905 was "sour."

Compared to the ever-so-slightly-euphonic m903, the m905 took a decisive step in the direction of complete tonal neutrality. Grace's website characterizes the m905's sound as "bracingly open." I can't argue with that. The m905 also had greater dynamic power and somewhat better-defined bass than the m903. That's hardly surprising; Michael Grace tells me that there's almost no carryover between the m903 and the clean-sheet-of-paper redesign of the m904 into the m905.

I'm sure that some of the differences I heard between the m903 and m905 were the results of many things, especially the design and build budgets. But one important factor might be that there's more room in the m905's two-rack-unit case for larger parts in those circumstances when a larger part is required to get better sound, the prime example being capacitors. Michael Grace: "Larger capacitors allow for lower corner frequencies."

Grace also said that his company recognizes that many m903 users are in what he calls a "recreational-listening environment," while the m905 is intended for "professional playback." To me, at least, that suggests that a lot of the m905's superior sound just wouldn't fit into the m903's smaller case (and roughly 45% lower price).

To make sure that my review sample of the m905 worked as advertised, I listened to a small selection of DSD downloads courtesy the "Test Bench" page of Norwegian record label 2L, using Channel D's Pure Music software for DSD playback. They sounded phenomenal. 2L records in PCM using DXD equipment from Digital Audio Denmark; PCMophobes might prefer their own test tracks of (allegedly) faultless provenance.

I leave the last word on the DSD kerfuffle to Michael Grace: "You can't say that DSD doesn't have a friendly, warm, smooth, musical sound; but that's not because DSD is 'technically superior' to other digital formats."

Pure PCM hi-rez recordings from my own pipe-organ project, 24/96 downloads of the Cypress String Quartet's recordings of Beethoven's late quartets (Cypress 5637890958), and a recording by the Bill Evans Trio of "My Foolish Heart" (24/192 download, HDtracks)—all sounded glorious. Regardless of sampling rate, the word that kept coming to mind was centeredness. "Red Book" recordings sounded great too.

In the grand scheme of things, there's yet life left in the CD format. A pleasant new discovery that arrived right just before deadline was Autograph, pianist Alexandre Tharaud's recital of 23 encores, most of them Romantic or Romanticized (CD, Erato 34137). Tharaud's clean, straightforward, non–self-indulgent performances let the music speak for itself. That, of course, requires scrupulous attention to rhythmic flow and to the interplay of voices, and excellent finger control. Alexander Siloti's arrangement of the Prelude in B Minor from J.S. Bach's Clavier-Büchlein vor W.F. Bach is a standout. There is a making-of video on YouTube. Especially recommended to piano fans.

Is there a Grace Design m905 in Your Future?
I am totally knocked out by the Grace m905. It has made its way onto the short list of the most impressive pieces of audio gear I have ever evaluated (footnote 2). Costing only $1500 more than the award-winning m903, it sounds decisively more commanding, and even more engaging. Furthermore, the m905 has a wealth of features and control functions that qualify it to serve as the heart of any but the most ambitious systems. If you're in the market for a high-performance DAC, the m905 is a screaming bargain and a no-brainer. Class A+, in my opinion.

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Footnote 2: The rest of the current list (from memory, with some other unmentioned pieces not entirely forgotten but dwindling in the rearview mirror): Meridian Control:15 music server; Bricasti Design M1 DAC; darTZeel NHB-108 and Lindell AMPX stereo power amplifiers; Cardas Clear interconnects and speaker cables; Harbeth P3ESR, Shahinian Obelisk, Vivid Audio K-1, Wilson Audio Alexandria II, and Wilson Benesch ACT One loudspeakers.—John Marks