You can’t swing a dead cat at an audio show without hitting a couple of dozen new DACs, introduced by both established manufacturers and start-ups, ranging in price from $99 up to the cost of a luxury automobile. The new entrants join the literally hundreds of DACs already available. Virtually all of them can play high resolution PCM audio up to 192KHz/24-bit, and increasingly up to double-DSD as well. In fact, if a new DAC can’t play DSD files, it is commercially dead in the water notwithstanding that, contrary to what some audio journalists and industry pundits would have you believe, there really isn’t very much DSD music available outside of some new recordings from small classical labels and vintage jazz transferred from analog tape.
I am sure that most of you are familiar with the psychological theory advanced by Swarthmore College professor Barry Schwartz known as The Paradox of Choice. In a nutshell, although common sense might lead you to believe that the more choices you have available the better, the hypothesis is that when presented with too many choices a consumer can become paralyzed and unable to make a decision, or the experience becomes so unpleasant that the consumer abandons the project. I know this to be true first hand. For example, a few years ago we “needed” a new light fixture for our breakfast room. My wife and I went to the local lighting gallery and, upon entering, I was overwhelmed with what must have been thousands of different choices on display overhead. I lasted about five minutes and headed back to the car, concluding that our existing light fixture wasn’t so bad after all. I’d say we may be approaching that situation given the number of DACs on the market, if we are not already there.
To navigate your way through the available models you need a strategy. The first thing you need to do is to be honest with yourself and set a firm budget, because the DAC that you think you really want is always twice as much you have to spend. That will winnow down the choices considerably. Then, since basic features are ubiquitous and easily sorted, you need to focus on the expertise of the manufacturer. What does it bring to the table in terms of engineering skills and experience? The truth is that if you can read a schematic and handle a soldering iron, you can build your own DAC. Each DAC chip comes with a model circuit for implementation of the chip’s features. These circuits generally involve only a few components and a power supply. At the low end, many manufacturers – including those whose names are readily recognizable – simply build the model circuit with minor changes and put the resulting DAC in a fancy (or not so fancy) case. It is why a lot of DACs using the same DAC chip sound the same. On the other hand, a manufacturer with considerable engineering skills can design a DAC to a price point without relying on the generic circuit approach, and push the state of the art even in its less expensive offerings. This is where the astute audiophile can separate the wheat from the chaff when drawing up a short list of DACs to audition, and ultimately when making a purchase decision.
Take Meridian for example. Although it uses the same DAC chips as many other manufacturers, rather than relying on the digital reconstruction filter built into the chip, it writes its own code to implement proprietary minimum phase apodizing filters even in its entry level products based on years of psychoacoustic research in developing its reference components. Other manufacturers with extensive digital expertise, including AURALiC, Ayre, and Bricasti, among others, offer the user a choice of proprietary digital filters developed in-house and implemented in field programmable gate arrays (FPGAs). At the other end of the spectrum are companies, like dCS, which, in addition to providing a selection of proprietary digital filters, eschew the use of DAC chips altogether, and instead build their DACs using mil-spec discrete parts in proprietary designs. Another example would be companies like EMM Labs, Playback Designs, and PS Audio, who use novel strategies such as converting all PCM to a DSD before processing to (ostensibly) achieve better performance.
Which brings us to the DAC under review – the Exogal Comet ($2500) DAC, or “Digital Audio Rendering Point” as Exogal likes to refer to it. I first ran across references to the Comet in May in snippets of coverage of the Munich Hi-End 2014 Show. I didn’t give it much attention. I had never heard of Exogal and assumed it was just another DAC from a small European shop whose products would never make it to these shores. Then I received a press release in July and learned that it was, in fact, an American company founded by four veterans of the high-end audio industry – Jim Kinne, Larry Jacoby, Jan Larsen, and Jeff Haagenstad. Jim Kinne and Larry Jacoby were the original founders of Wadia, with Jim doing all of the hardware and software design work and Larry handling the industrial design and business functions (Larry was also one of the co-founders of Stillpoints). They remained with the company until 2000, when Wadia was sold and, without Jim and Larry at the helm, subsequently lost its way. Jeff Haagenstad joined Wadia briefly in 2011 and remained until it was transferred to McIntosh a year later. Jim, Larry, Jan, and Jeff founded Exogal in 2013. Their first product is the Comet DAC, though more products are in the concept and design stages, including a 125w/250w Class D power amplifier tentatively designated as the Ion.
Description and Setup
The Comet is a compact component, measuring just 11.5 inches long by 7.45 inches deep by 1.875 inches high, and weighing 8.75 pounds. Not surprisingly, given its weight, the Comet’s casework is CNC-milled from a solid anodized aircraft-grade aluminum billet rather than the more common bent metal or plastic, giving it a look and feel significantly more imposing and attractive than other DACs in its price tier. On the front panel, there is only a small monochrome display, showing volume and input, and whether the output is set to the main balanced (XLR) and unbalanced (RCA) output connectors on the rear panel, or to the 1/4″ stereo headphone jack on the right side. The headphone jack is a real bonus. Many fine DACs, like the AURALiC VEGA, Bricasti M1, dCS Debussy, and Meitner DAC1, don’t have one, requiring that you invest in yet another box for headphone listening. The display is intentionally not back-lit, eliminating yet another laser-like blue light from your rack. McIntosh aficionados, enamored with big flashy meters, need not apply. Welcome to the age of the smartphone!
On the rear panel, in addition to its dual outputs, there are coaxial (BNC), Toslink, AES/EBU (XLR), and asynchronous USB inputs. Like the similarly priced Benchmark DAC2 HGC, the Comet also has an analog input, making it perfect for someone having an analog front-end in addition to his digital sources, obviating the need for a separate preamplifier. Output volume is variable both on the main outputs and the headphone output. Analog to digital conversion is done at 96/24 and then upsampled to 384/24. Two HDMI style jacks are available for connection to future Exogal products. Another bonus is a USB jack for charging your iPhone, iPad, or Android device, There is also a mini-jack for triggering other components, including your integrated or power amplifier if it is so equipped. Finally, there is a DC input jack for the large inline SMPS power supply. No wall warts here. Everything is logically laid out, though compact in execution.
The Toslink input accepts PCM up to 96/24; the coaxial (BNC) and AES/EBU (XLR) inputs accept up to 192/24; and the USB input accepts up to 384/24 and up to double-DSD over DoP. PCM inputs from 44.1KHz to 96KHz are upsampled to quad rate (176KHz or 192KHz). Unlike some manufacturers which convert PCM to DSD prior to processing, Exogal adheres to the technical position espoused most coherently by Berkeley Labs, and converts DSD64 to 176.2/24 and DSD128 to 352.4/24. It is refreshing to see this openly articulated. Most manufacturers are silent as to exactly what happens to DSD streams during digital to analog conversion. Who knows what evil lurks in the hearts of DACs?
The Comet is not a cookie-cutter DAC. All of its DSP and other processing, the core of a DAC’s design, occurs in a proprietary FGPA programmed by Jim Kinne. Four digital reconstruction filters are available – one linear phase, two minimum phase, and one spline. The actual DAC chips are only used for the final digital to analog conversion. And, uniquely, there are six of them, one for each of the left and right channels of the balanced, unbalanced, and headphone outputs. By using multiple DAC chips and an open architecture FPGA, the Comet has the flexibility to be reconfigured to allow center channel/subwoofer output. A basic key fob style remote control is included, though Exogal has written iOS and Android apps for your iPhone, iPad, and Android devices. Remote access with the apps is transmitted over Bluetooth Low Energy.
Setup was straightforward. Except when evaluating the analog to digital conversion in the Comet, I connected my VPI Scout, via a Musical Surroundings Phonomena II phono stage, to the analog input of the Comet; I connected my Mac Mini to the USB input; and I connected my Meridian G08 CD player to the coaxial digital input using an RCA to BNC adapter. I then connected the balanced outputs of the Comet directly to Pass Labs XA100.5 monoblocks, and then on to Magnepan 1.7 loudspeakers. All cabling was Kimber Select. Headphone performance evaluation was done with Etyomotic ER-4s in-ear monitors and Sennheiser HD800 headphones.
The first aspect of the Comet I wanted to gauge was its analog to digital conversion on the analog input. I listened, for example, to Vladimir Horowitz’s first recorded version of Beethoven’s Piano Sonata No. 8, Op. 13 “Pathetique” on the Columbia Masterworks label. Initially, to establish a reference, I connected my phono stage to one of the analog inputs of my Meridian G02 preamplifier. Opening somewhat ponderously but moving quickly to a more propulsive pace, there was a decently wide soundstage for the age of the recording, with the piano appropriately sized both sonically and visually in the center. Small details abounded, including the presence of mechanism noise and lingering note decay. The bass was somewhat lacking and the treble not overly extended, again attributable to the age of recording, resulting in an emphasis on the midrange (which is fine as that is where most of the music resides) rendered with warmth and hint of bloom. There was some surface noise present, but it was not emphasized. The second movement, tenderly played, was emotionally engaging. Timing of this section of the sonata is especially critical, especially the silences between notes, and the Meridian G02 did nothing to impede or adjust its flow. The third movement picks up the pace significantly. With many notes played rapidly and with liberal use of the sustain pedal, even so the melody remained delineated rather than slurred. The fourth movement calls for a big sound, as all the stops are pulled out, and here the dynamics were well portrayed, the sound expanding to fill the room. Overall, the combination presented a very pleasant and engaging sound.
Then, I connected the phono preamplifier directly to the analog input of the Comet and re-listened. To my ears, the sound was almost identical. Perhaps the sound was ever so slightly more neutral and the groove noise slightly more present when routed though the Comet. If indeed it was, I would attribute that to a mild coloration in the Meridian G02 rather than anything clinical about the Comet. Meridian is known for its warm, smooth presentation, so this was no surprise. At least in the context of my system, I would deem the digital to analog conversion of the Comet neutral and transparent, and except for its flexibility for review purposes, I would gladly forego my preamplifier with the Comet in my system. The choice, however, would be system dependent and hinge on personal preference. For example, if you were particularly fond of the sound of your, say tube, preamplifier, you might come to a different conclusion. It is unlikely, however, that the Comet would be the component adding the sonic signature.
I found the same slight additional smoothness and warmth when I compared CD playback running the analog outs of my Meridian G08 CD player to through the G02 preamplifier on the one hand to the G08′s digital output fed directly the Comet on the other. Based on prior experience, and confirmed when evaluating the Comet, the DACs in the G08 have the same Meridian house sound as the G02, with both in the system having an additive effect. Again, unless you had a clear preference for the Meridian sound, foregoing reliance on the G08′s internal DACs and the G02′s extra gainstage in favor of the Comet would be an easy call. This portends well for the Comet serving double duty as an effective upgrade to an aging CD player you would like to keep in your system even though you have moved inextricably to computer playback.
Substantially all of my listening was done from the USB output of my Mac Mini, freshly updated with the latest version of Apple’s Yosemite operating system. I use iTunes for file management and Audirvana Plus (also freshly updated to version 2.0) for playback. The Mac Mini instantly recognized the Comet, without the commonplace who’s on first runaround of alternately powering on one then the other to establish a connection. It just works.
I suppose it is because I grew up in Texas and, as a kid, listened to Western swing on Saturday nights during the Country and Western TV shows that came on before the sci-fi/horror classics at 10:00 p.m., that explains why I am a fan of the group Asleep at the Wheel, which, if you didn’t know better, you would think was the incomparable Bob Wills and the Texas Playboys. It is feel-good music that will put a smile on your face and a lift in your step at the end of a long day when you don’t have the energy or intellectual wherewithal to deconstruct the 24 Preludes of Scriabin. Think fiddle, pedal steel, rhythm guitar, a modest pulsing drum kit, traditional lyrics of hard drinking and lost love, and a judicious bit of cowboy yodeling. Folks, you are just not going to run across this music mentioned in reviews from the mainstream audiophile press. If you’re interested in stretching beyond your current musical boundaries, pick up a copy of Ride With Bob. It’s a tribute album of the finest kind, chock full of contributions from over two dozen star country performers.
Take Faded Love, for example. Crooners Lucinda Williams, Shawn Colvin, and Lyle Lovett join Asleep at the Wheel band members in this classic penned by Johnny Gimble and the Wills brothers. Sparsely orchestrated, the sweet sounding fiddle takes center stage for the opening, joined by bass and drums in the background keeping time with distinctive thump and tap throughout, and piano adding accents until the pedal steel guitar takes its turn adding an appropriately forlorn atmosphere to the tune. While separation of instruments is not laser-like, is not intended to be. Instead, there is a blending of instruments, with the spotlight on the individual vocals, as if the band is being heard from further back in the dance hall rather than right up front next to the stage. This blending was done at the mixing board during recording, and not by the Comet at playback. The Comet just gets out of the way rather than drawing attention to itself, and lets the music speak for itself. Isn’t that how it should be?
Joshua Bell burst on the classical music scene in 1981 at age 14 as a soloist with the Philadelphia Orchestra conducted by Riccardo Muti, and hasn’t looked back. Unlike many prodigies, whose careers are fleeting, Joshua Bell has been dazzling audiences for over 30 years with his violin pyrotechnics. He is in continuous demand as a soloist worldwide, and is currently the Music Director of the Academy of St. Martin in the Fields, succeeding founder Sir Neville Marriner, who had led the chamber orchestra since its inception in 1959. One of my favorite of Joshua Bell’s recordings is The Kreisler Album, a compilation of encores, codas, and short original compositions by, as the title suggests, Fritz Kreisler. My admiration for the recording arises not out of an inability to focus for more than a few minutes at a time, but from the sheer virtuosity the pieces require. They often leave me breathless.
That Joshua Bell, playing his 1714 Gibson ex Huberman Stradivarius, is able to wrest such an achingly beautiful tone while his fingers are flying over the neck is nothing short of miraculous. For example, Tambourin chinois is lightening fast, yet the sound is sweet, and there is never any harshness with notes played way up the neck on the E string. Screeching is not even is his vocabulary – or that of the Comet, which is seemingly built for string tone. That is the case even though the miking is close, where such faults are often magnified. The violin sound is strong and resonant, with the instrument under complete control. All of the pieces, however, are not spark and sizzle. La Precieuse is playful, with many notes held for a long time, with the small pitch variations from the vibrato easily distinguished as the tone fades. I would be remiss if I did not also mention the sound of the piano which accompanies these bon-bons. Located center, but behind the violin, it is flowing, supporting, but never encroaching, and with the pace always shadowing the violin without exception. Much the same can be said for Liebesleid. The Comet renders the entire CD delightfully.
Having focused primarily on the upper midrange and treble performance of the Comet is not to diminish its talent in the lower midrange and bass departments. Bach’s Unaccompanied Cello Suites, transcribed for double bass and performed by Edgar Meyer, offer the perfect foil. The double bass, tuned in fourths rather than fifths, accordingly sits somewhat less than one octave below the cello. This gives it a more growling, reverberant sound, especially when played arco rather than pizzicato. Easily recognized, Suite for Solo Cello No. 2 in D minor begins slowly in a haunting manner, substantially free from double-stops, which allows the individual notes to ring freely. The deep notes are, despite such extended quivering, taut and distinct, with the floor vibrating sympathetically due to close coupling with the loudspeakers. As the notes fall, the instrument seemingly grows in size, resulting from the sound spreading throughout the room. As the tempo increases, the decay shortens. The overarching sound is woody and resonant. Unlike some DACs in this price range, the Comet fully fleshes this out, rather than sounding somewhat thin and less robust. This is also evident in the overtones which reach into the midrange adding harmonic richness with a tone cut from the same cloth. There is simply little to fault in this aspect of the Comet’s performance.
As you would expect, the headphone output is likewise neutral and transparent, and revealing in the good sense of the word. If you want that glowing burnished sound, seek out a Woo. The Comet has more than enough oomph to drive both my Etyomotic ER-4s IEMs and Sennheiser HD800 headphones to deafening levels without distortion. A word of warning: sois sage with the volume level. At normal volume settings, music is engaging, with firm bass underpinning, clean midrange without undue emphasis, and extended treble free of thinness and etching. It is just pleasant to listen to, including during extended sessions when little faults in presentation are otherwise most likely to result in listener fatigue. And its 1/4″ rather than 3.5mm headphone jack opens up a wide selection of audiophile extension cables to choose from. The Comet’s headphone output is clearly no afterthought.
While I will not be parting with my dCS Debussy as a result of my time with the Exogal Comet, based on my experience auditioning a score of other DACs in all price ranges in my reference system, given its flexibility and performance, at less than a quarter of the price, the Exogal Comet has few if any peers in its class. It covers all the bases, accepting PCM up to 384/24 and decoding double DSD. With a complete panoply of input options, you will not be left wanting for connectivity. It is especially recommendable given the inclusion of its analog input, transparent analog to digital conversion, variable volume control, and eminently capable headphone output. With both balanced and unbalanced outputs simultaneously active, audiophiles with subwoofer(s) in their systems will be particularly grateful. The USB charging port for iDevices is icing on the cake. And the resulting sound left little to be desired. I was impressed to say the least. The overused “Swiss Army knife” designation originated by John Atkinson nearly two decades ago in his review of the Meridian 518 digital audio processor is appropriate here. My hat’s off to the industry veterans at Exogal. The execution and performance of the Comet prove that talent and experience are a powerful combination.
- Frank Berryman
Digital Inputs: AES/EBU on XLR, SPDIF on 75Ohm BNC, Toslink, USB-B, analog on isolated RCA
Formats: 16-24 bit, 44.1KHz-384KHz; DSD64 and DSD128
Analog Input: one pair unbalanced RCA
Analog Outputs: one pair balanced (XLR), one pair unbalanced (RCA)
Weight: 8.5 lbs, 3.81 kg
Dimensions: 1.875 x 7.45 x 11.5 in., (47.6 x 190 x 292 mm)
Finish: anodized aluminum
Analog Source: VPI Scout; Dynavector 20X2; Musical Surroundings Phonomena II
Digital Sources: Meridian G08; Mac Mini; dCS Debussy; Audirvana Plus
Preamplifier: Meridian G02
Power Amplifier: Pass Labs XA100.5s
Loudspeakers: Magnepan 1.7
Analog Cables: Kimber Select KS1016 and KS1116
Digital Cables: Kimber Select KS2020 and KS2416 USB
Speaker Cables: Kimber Select KS6063 and KS9033
Power Cables: Kimber PK10G and PK14G
Headphones: Etyomotic ER-4s; Sennheiser HD800
Accessories: Audience aR2p power conditioner