Digital Processor Reviews

Watts again: "Bob Cordell proposed nested feedback loops in the 1980s as a way of improving amplifier performance. . . . [W]hat he was proposing was equivalent to a second-order analog noise shaper [that] eliminates distortion. There is a huge amount of negative feedback available with a nested feedback stage, even at 20kHz. The benefit is that when you plug in a 33 ohm load, there is no increase in distortion at all. In all my DACs I've got a very simple analog structure. From Mojo right up to DAVE, it comes down to two resistors and two capacitors and a single amplification stage . . . which gives us much greater transparency. There is also a digital DC servo in the circuit, so there's no coupling capacitor: the error signal is fed to an A/D converter and cleaned up, before being used to eliminate DC at the output."

Setup and Use
The DAVE's display has four zones: the top half displays the selected input, sample rate, and volume level; in Display modes 1, 3, and 4, the background color reflects the rate and volume (Display mode 2 is black and white). The middle two sections of the screen show the setup options: PCM/DSD, Phase (Polarity), HF Filter on/off, and Display mode. The bottom section shows whether the Chord is set to DAC mode (fixed output), Digital Preamplifier mode (volume control active), or Headphone mode (plugging headphones into the front-panel jack mutes the main outputs).

As I was going to use Chord's DAVE without a preamp in the system, I used its button array to set it to Digital Pre mode by scrolling down the displayed options until the operating mode was highlighted, then pressing the left and right buttons simultaneously. The big central button then acts as a volume control; pressing it mutes the output. Inputs are selected by pushing the left and right buttons. If both these buttons are pressed simultaneously while the D/A mode is highlighted, the user can select the PCM Plus or DSD Plus filter. (The Chord mutes for 20 seconds after either is selected, while the circuitry stabilizes.) The top-panel controls are duplicated on the remote control, but as this has buttons to control other Chord products, it's way more complicated than it needs to be.

I had one operational glitch with the DAVE: the bodies of the connectors on my TosLink cables were too big to allow them to be locked in place when plugged into the rear panel, though the input did lock on to optical S/PDIF datastreams.

Sonics
The DAVE arrived in my system while I was preparing the CD masters for Stereophile's Tight Lines project, a collection of Sasha Matson's compositions for chamber ensemble. I was trying out different dithering algorithms to reduce the 32 bits of the master files to the 16 necessary for the CD release, and with the DAVE turning the digital bits to analog waves, I could arrive at the optimal dither relatively quickly.

Although Tight Lines was recorded with multiple mikes in a Hollywood scoring studio, engineer Michael C. Ross had captured good soundstage depth, and his work was readily evident through the DAVE. There was again superb soundstage depth with a favorite orchestral recording, Charles Dutoit's performance with the Montreal Symphony Orchestra of Mendelssohn's A Midsummer Night's Dream (16/44.1 ALAC files ripped from CD, Decca 417-541-2). The woodwinds in particular—in the Scherzo, for example—were each set well behind the plane of the speakers.

Tasmanian reader John Coulson recently e-mailed to say how much he had enjoyed Stereophile's Encore, a selection of chamber works by Brahms and Mendelssohn that I'd recorded live at the Santa Fe Chamber Music Festival in 1997 (CD, Stereophile STPH011-2). I hadn't listened to this album in a couple of years, so I selected the 16/44.1 files in Pure Music on my Mac mini and pressed Play while I sat at my desk, working on some copy. Darned if I didn't have to go sit in the listening chair, so compelling was the sound produced by the DAVE. I hadn't remembered there being so much depth to the soundstage, or the instruments being so securely rooted in the acoustic of the St. Francis Auditorium. Marji Danilow's appropriately gruff-sounding double bass provided a solid foundation to the music making, and pianist Christopher O'Riley sets some fast tempi in the finale of the Mendelssohn Sextet that make other recorded performances seem very staid.

The DAVE did indeed do well with piano. O'Riley's notes were very well defined, placing the instrument solidly between and behind the speakers. I switched from Pure Music to the Tidal desktop app and called up Daniel Barenboim's recent solo recording of Liszt's arrangement of Solemn March to the Holy Grail, from Wagner's Parsifal, from On My New Piano (16/44.1 Tidal HiFi stream, Deutsche Grammophon 289 479 6724). The deep tolling bass notes of Barenboim's unique straight-strung piano sounded majestic with the DAVE in the system. On to CD, with my Ayre Acoustics C-5xe^MP feeding the DAVE AES/EBU data: Evelina Vorontsova's hauntingly beautiful performance of Rachmaninoff's Piano Sonata 2 sounded rich, detailed, and yes, again, majestic (CD, STH Quality Classics 1416092). The DAVE is the DAC for lovers of recorded piano.

I've mentioned recordings of orchestral and chamber music and solo piano; what about rock? Before leaving for last January's Consumer Electronics Show, I used the Vinyl Studio app with Ayre's awesome QA-9 A/D converter to rip some 12" 45rpm singles to 24/192 AIFF files, including Joe Walsh's "Rocky Mountain Way" (ABC ABE 12002), which has probably the most dynamically recorded drum sound ever. Back home, after having stretched the dynamic-range envelopes of several systems at CES almost to their breaking points—as I wrote in these pages years ago, you just can't play "Rocky Mountain Way" at anything less than head-banging SPLs—I played the track with the DAVE feeding the monstrously powerful MBL Corona C15 monoblocks driving Rockport Technologies Avior II speakers. Heads were banged, walls were shook, feet were set a-dancing—the DAVE delivered the dynamic goods!

Comparisons
The obvious comparison was with Meridian's Ultra DAC ($23,000), which I reviewed in the May issue. The Meridian offers MQA decoding, the Chord doesn't; so to somewhat level the playing field, I used the latest version of the Tidal app (2.1.5) on my Mac mini with the MQA Passthrough button unchecked (this allows Tidal to perform the first unfolding of MQA files), feeding 2Fs data to the DAC. With Tor Espen Aspaas's performance of Beethoven's Piano Sonata 32 in c, Op.111, from Mirror Canon (Tidal Master stream, 2L 2L-049-SACD), the 44.1kHz-sampled data were unfolded to an 88.2kHz stream, according to the DAVE's display. Even without MQA decoding, the sound of the piano was reproduced with superb force in the lower registers. Aspaas takes the second movement's stately opening Adagio slower than I'm used to, but what erstwhile Stereophile columnist John Marks described as Aspaas's "wonderfully poetic playing" was extraordinarily compelling.

I rechecked the MQA Passthrough button, to send the 24/44.1 MQA stream to the Meridian to let it perform all the MQA unfolding. Its display read "352k," and I set the playback level to be the same as with the DAVE. Superficially, the sound with the Ultra DAC was identical to that with the DAVE: same pianist, same piano, same hall. But after a while, I became just a little bit more aware of how the harmonic envelope of a note changed as it died; the pianist's touch on the keys was just a little more developed with the Meridian fully decoding the MQA data. Yes, this was a subtle difference, but not an unimportant one in the context of DACs costing five figures.

For a fairer comparison, I tried both DACs with DSD files sourced from the Aurender N10 music server via USB, specifically violinist Christian Tetzlaff's performances of the third Brahms sonata, accompanied by pianist Lars Vogt (DSD128 files from HDtracks, Ondine ODE12842), and set the DAVE to its DSD Plus mode. With the DAVE decoding the bits, both instruments were presented with precise stereo imaging, natural-sounding tonalities, and with the piano's left-hand register offering the weight I'd noted earlier with PCM files. Perhaps the violin didn't have the quite the seamless top end I was expecting from my earlier listening, but this was still a first-rate presentation of this emotionally charged music.

Switching to the Meridian with levels matched, the sound was warmer, with less weight to the piano's bass notes but a slightly mellower violin. Given my druthers, I'd combine the Chord's piano reproduction with the Meridian's violin tone.

Conclusions
I very much enjoyed the time I spent with Chord Electronics' DAVE. Its superb re-creation of soundstage depth, its sense of musical drive, and the clarity with which it presented recorded detail were addictive, though that clarity did demand that ancillary components be equally high performing. And the DAVE's price is considerably lower than that of the high-achieving DACs from Meridian and dCS that I have reviewed.

There are two unanswered questions, however. One is practical, in that as systems increasingly become network-based, the DAVE's lack of an Ethernet port might eventually become a limitation. The other concerns MQA. If that format gains in acceptance, then the DAVE will never be able to get the best from it: MQA's and Rob Watts's ideas on filter design are incompatible.

Which leads me to a final point: As much as I was impressed by the DAVE, my experience left me puzzled. In recent years I have become convinced that the best sound from digital in general is to be gotten from DACs that use very short reconstruction filters: Ayre Acoustics' Listen filter, for example, and the equally short filter used by MQA decoders. And I've found that minimum-phase filters, as used by dCS and Meridian processors as well as by Ayre, tend to sound more natural than the usual linear-phase filters.

But here I am, recommending a DAC with a linear-phase FIR filter that is not merely long but the extreme opposite of short. What gives? To stretch an analogy: If perfect sound quality lies on the other side of a mountain of implementation, the short, minimum-phase filter route goes one way around that mountain, and the long, linear-phase filter route goes the other way. But on the far side of the mountain, the two routes begin to converge . . .

All I can say is that you must listen to the DAVE for yourself.