Esoteric K-03 (TAS 213)

Equipment report
Disc players
Esoteric K-03
Esoteric K-03 (TAS 213)

The Esoteric K-03 is not your usual CD/SACD player. Its designers have innovatively combined a highly refined CD/SACD transport and a full-function DAC within the same luscious chassis. Although on the surface that doesn’t seem so unusual, consider that very few digital players even bother to include an input for external devices like PCs, music servers, and cable boxes. Many is the time I wished I could plug one or more of those sources into a CD or universal player that I knew had a great internal DAC. Recently, more designers have incorporated the digital input feature into their players. But even those models generally offer only one such input, and that interface is virtually never USB.

In contrast, the K-03 is a real DAC. There are three digital inputs—coax, TosLink, and USB—as well as filter and oversampling options, just like an outboard unit. There is even an input for an external word clock. You won’t see that on many other digital players. Nor is the USB input an afterthought; it offers asynchronous clocking via one of multiple drivers, and supports the highest bit rates. The benefit of Esoteric’s approach is compelling: Owners get the inherent sonic advantages of having the transport and DAC in one box, along with the versatility and multi-source support normally available only from stand-alone DACs.

This benefit also carries over to the K-01, the K-03’s big brother. Although I begged for the $22,500 flagship, with its quad power supplies, magnesium disc clamp, and sixteen(!) DACs, a sample could not be made available in time for this issue. I was forced to “settle” instead for the penultimate $13,000 K-03. This model makes do with just two power supplies, a Duraluminum clamp, and a paltry eight DACs. Specifically, the K-03 employs eight 32-bit AKM DACs (four per channel). The two units do not share identical transports, either, but they do have the same new clock and discrete, fully balanced analog modules.

Besides being a hybrid player/DAC, the K-03 is also unusual in that it requires a great deal of configuration before it can—or should—be used. Most digital players are plug-and-play, but if you do that with this one you will not experience anything like its ultimate sound. Unfortunately, setup is no small task. First, one must endure a break-in period that amounts to over a month of continuous play. The second complication is due to those aforementioned upsampling, filter, and driver options. There are four upconversion choices, three USB drivers, and five filter settings. If that isn’t enough, the settings interact with each other, thus requiring a listen to every combination in order to find the best—a rather daunting proposition.

And it needn’t be, because it turns out quite a few of these options are clearly inferior and could have been omitted without sacrifice. Why they were included is a puzzle. If you are curious about my adventures in Optionland, they are recounted in the sidebar, “A Surfeit of Settings.” If not, I can still save you a lot of trial and error by telling you that the “S_DLY1” apodising filter is the best, the choice between 2x and 4x upsampling is a matter of personal preference (although either one stomps the other options), and the asynchronous “HS_2” USB driver is the only one worth considering. I should also note that none of these is among the unit’s default settings, which are invariably the worst in their respective category. Another puzzle.

Thankfully, configuration needs to be done only once. The K-03 may not be plug-and-play, but at least it’s set-and-forget. And once set, any lingering consternation begins melting away. From a functional standpoint, the Esoteric has the silky-smooth operation, the weighty remote, and the rock-solid reliability one would expect in this price range. There are thoughtful touches, too, like the way the menu takes you to the parameter you last changed.

The K-03 has quite a few operating modes, and most—but not all—of them deliver reference-quality sound. Surprisingly, the least impressive (which is not to say unimpressive) mode is CD playback. I’ll explain why this is so surprising later on, but for now let me describe the sound. First the good news. With CDs, the K-03 sounds beautiful, delivers exceptional detail and spatial depth, and is tonally ravishing. On the other hand, it is missing the ultimate resolution, openness, and freedom from digital edginess that makes today’s reference gear so relaxing and engaging.

For an illustration, listen to “Bydlo” from the Sir Colin Davis rendition of Pictures at an Exhibition [Philips]. Although this is not a stellar recording overall, the track is a good test of timing and resolution. With respect to the former, the low strings that open the track should maintain a lumbering pace but should never plod. Through the K-03, plod they do. As for resolution, listen to the snare drum that enters at about 1:30 into the track. Through my reference player—a combination Goldmund Mimesis 36 transport and the dCS Debussy DAC—the snare drum’s “papery” quality is quite distinct. On the Esoteric, that quality is missing, as are other subtleties such as the hall acoustics that surround and firmly place the solo horn’s position at the rear of the stage.

Of course, my reference rig is significantly more expensive than the K-03. Heck, the dCS all by itself costs nearly as much as the Esoteric player/DAC combo. My disappointment with the latter’s CD sound is not so much because it does not equal the reference gear, but because it does not equal its own performance in other modes. So now that I have CD out of the way, let me turn to those.

First and definitely foremost is SACD playback. Simply stated, the K-03 is the best SACD player I have heard—not by a mile, by a marathon. When playing my standard SACD torture test, Stravinsky’s Suite from l’Histoire du Soldat [Pentatone], the Esoteric imbues both strings and horns with a heretofore unheard burnished quality that amps up the disc’s already astonishing realism. The K-03 brings out—but never exaggerates—every detail. Nor is there a trace of edginess, and music has tremendous drive. As good as this hybrid disc’s CD layer sounds through my reference system, the K-03’s SACD rendition simply annihilates it.

This difference is not simply due to the higher inherent resolution and analog-like nature of the SACD format. I played, for example, the “Out of the Woods” track from Nickel Creek’s eponymous first album through the estimable Marantz UD9004 universal player. The Marantz ably captures the liquidity that differentiates SACD from CD, but the UD9004 does not come close to matching the musical scale and sonic clarity of the K-03.

I was in for another treat when I connected my CD transport to the Esoteric’s coax input. Oh my, the K-03 is one sweet DAC. As with SACD playback, rhythms are unflagging, details emerge clearly and naturally, and listener fatigue is non-existent. Dynamics are superb as well. All of these factors raise the emotional quotient mightily. Indeed, as a pure DAC, the Esoteric is very much in dCS territory. It can’t quite match the latter’s sublime effortlessness and bass definition, but the Esoteric feels more open and light on its feet.

By now it should be apparent that playing CDs through the K-03’s DAC via an external transport yields results that are distinctly superior to the all-in-one mode. Take “Bydlo,” for example. Using an external transport, those previously missing hall acoustics reappear. Further, the external transport wrings out all the music’s drama, while the internal transport is emotionally circumspect. On a raft of material the K-03’s DAC always proved more detailed and neutral—and therefore more enjoyable—when driven externally.

This should not be the case. Self-contained players at this level almost always sound better than an outboard transport, no matter how good, driving their DAC. The benefits of eliminating an S/PDIF connection and having a single master clock are nearly insurmountable. That the Esoteric does not follow this pattern is particularly puzzling. The only explanation I can see is that the K-03’s internal transport, for all its pedigree, is holding back the unit’s CD sound. Obviously, though, this comment does not apply to that same transport playing SACDs.

Back to the K-03 as a DAC, there is still USB to discuss. Here, again, Esoteric offers options. Three drivers are available. The first will load automatically when you connect the K-03 to a computer, while the other two must be downloaded from Esoteric’s Web site. As already mentioned, I experienced the best results with “HS_2,” the only driver that supports asynchronous clocking. However, all three drivers sounded significantly better when supplemented with ASIO, which bypasses any and all OS detritus, so I highly recommend you download the free ASIO4ALL for your media player of choice (sorry, Mac users). Using ASIO has the added benefit of enabling the K-03 to automatically adapt to sample and bit rates, relieving you from manually setting those in the OS to match each source file you play—a major pain.

Once everything is set, the magic begins. I listened to the new 96/24 version of Tom Petty’s “Refugee”, downloadable from HDTracks, and the sound was stunningly open, clear, and revealing. From the same source I downloaded a high-rez file of Keith Jarrett’s Koln Concert and found it to be equally engaging. The real achievement of the K-03’s USB is that it seems to have banished entirely the artificiality that has plagued this interface. USB is a fast-evolving format, which is fortunate since it started out sounding so bad. Now, even though I proclaimed the dCS Debussy the best USB I had ever heard only a few months ago, I am bound to say that the Esoteric is even better.

Lastly, the K-03 can serve as a linestage. Like many recent digital players and DACs, the K-03 has a built-in volume control and can directly drive a power amplifier, obviating the need for a separate linestage so long as all sources are digital. In this mode, the K-03’s performance is largely dependent on the choice of music. Digital volume controls always cause a loss of resolution when they are turned down, and so pop/rock recordings, with their high mastering levels prompting a volume reduction, fare poorly. But classical music, which does not have hyped levels and so can be played with higher volume settings, sounded nearly identical to my reference linestage—an extraordinary accomplishment. Esoteric asserts that the K-03’s four 32-bit DACs per channel obviates any resolution loss introduced by the digital-domain volume control.

In sum, the Esoteric K-03 is a brilliant concept, and delivers in nearly every category. Though its builders went overboard on configuration options, the rest of the design is unassailable, as is its sonic performance in all but one area. CD playback is good, and disappoints primarily compared to the K-03’s SACD, DAC, and USB performance, all of which are of reference caliber. I would urge you to give the Esoteric a listen, to hear just how good these can be.

A Surfeit of Settings

Of the five filter settings, “None” is the inexplicable default. In this mode, the K-03 sounds airless and sickly, and dynamics are voting in absentia. “FIR1,” a fairly standard filter with a variable frequency cutoff, is much better, with a breath of air and a modicum of timbral resolution. Unfortunately, FIR1’s dynamics are so exaggerated that on accented notes I felt like I was being jabbed in the eyes. Moving along to “FIR2,” which is the same as FIR1 but with a fixed 80Hz cutoff, the sound takes on softer leading edges and dynamics are more manageable, though accents remain off-putting.

With “S_DLY1” we move into apodising filters and the difference is stark. The entire presentation is less in-your-face, and there is more air. Dynamics finally settle down into a natural stance, and a reduction in midrange bloat makes it easier to hear things like individual violin strings. Meanwhile, though “S_DLY2” is also an apodising filter, it seems to ring plenty. Moreover, this option doesn’t do much (though it does a little) to alleviate the issues I found with the FIR filters. FIR2 and S_DLY2 sound better or worse depending on the upsampling setting, but at their best neither compares with S_DLY1, the only option that really sounds “right.”

As with filters, “None” is the default upsampling setting. And as with filters that is a shame, for this setting is characterized by sluggish rhythms, coarse dynamics, and uninformative timbres. Switching to “2X Upsampling” reveals what a poor decision it would be to leave the K-03’s upsampling disabled. Here, rhythms snap into place and for the first time are unconfused. Also for the first time, instruments and dynamics can, when the music calls for it, display a degree of delicacy. “4X Upsampling” adds freer (but not exaggerated) dynamics and greater rhythmic swing, though this setting is not quite as clean-sounding as 2X.

“Upsampling to DSD” is an option for which I had high hopes. Selecting it, I was struck by how completely different it sounded compared to every other setting. On orchestral material, I almost felt as if I was listening to a different string section—one with a markedly darker sound. That’s not necessarily wrong (who knows how the real strings sounded), but the DSD setting was also noisier than—and not nearly as well-sorted dynamically as—the 2X or 4X options. As a result, in this mode certain pieces of music, like the second movement of the Vaughn Williams Sea Symphony, lose much of their mystery and subtlety. I therefore recommend choosing between 2X and 4X upsampling, either of which is a valid choice that will be determined by personal preference.

The standard USB driver, dubbed “Normal,” is not bad, but it suppresses depth and transparency. Adding ASIO reaps a marked improvement in both areas. Drums and vocals emerge as if from behind a scrim, dynamics flourish, and there is much more detail with no downside. Nonetheless, the “HS_1” driver is worlds better, and better still with ASIO. HS_1, though, betrays the synthetic string sound I hear from so much USB. “HS_2” is clearly the best of the lot, being more spacious and having better bass definition. Here, for the first time, ASIO does not make a night and day difference, though it does supply better-behaved rhythms and is generally airier.

As discussed in the main piece, ASIO would be recommended even if it sounded made no sonic difference, because it gives the K-03 the ability to dynamically adapt to the incoming source’s sample and bit rate. This is a feature no computer audiophile should be without. Its absence means either manually changing sample rates all the time, or leaving them set to the highest the OS will support, and suffering the harmful sonic effects of asynchronous upsampling.


Outputs: Stereo balanced analog, stereo balanced single-ended
Other connections: Coax, TosLink, and USB digital inputs; word clock input
Dimensions: 17¼” x 6 3/8” x 13¼”
Weight: 61.75 lbs.
Price: $13,000

TEAC America, Inc.
7733 Telegraph Road
Montebello, CA 90640

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