Esoteric K-03Reviewers' ChoiceI’m going to admit something that won’t make me very popular with the audiophile in-crowd. It’s not that many of my audio cables touch the floor and run parallel rather than perpendicular to each other (which they do). Nor is it that I occasionally listen to MP3 music files (which I do). Rather, it’s that I am not ready to give up on my substantial collection of CDs. 

Yes, countless people have told me that computer audio is the future. I get it. I am aware that CDs are inherently limited to a resolution of 16-bit/44.1kHz, and that high-resolution digital music files can sound significantly better than any CD ever could. I am also aware that computer audio offers a revolutionary way for me to access my music. 

However, many of my CDs sound great, and some of them provide absolutely stunning sound that makes people’s jaws drop when they hear them. So while I’ve jumped aboard the computer-audio train, my CDs are coming along with me. 

What’s a guy like me, who listens to both CDs and computer audio, to do? Well, a number of manufacturers have combined a computer-capable DAC and a CD player into a single component. Doing so arguably provides the best of both worlds. 

Esoteric, which has a rock-solid reputation for making high-performance disc players and other audio components, has made such combinations of products for some time. The subject of this review, Esoteric’s K-03 SACD/CD player and DAC ($13,000 USD), is one of their newest models of this type. In addition to playing CDs and digital music files, the K-03 also decodes SACD (DSD) bitstreams. In fact, it also contains a 32-bit internal volume attenuator that permits it to be connected directly to an amplifier. 

All of this told me to place the K-03 on my review short list. 

Features: a silvery Swiss Army Knife

The K-03 and its more expensive sibling, the K-01 ($23,500), sit at the top of Esoteric’s line of one-box “digital source devices,” respectively replacing the X-03 and X-01 models. On the K-03’s faceplate are a power button, an LED word status indicator, a source mode button, a remote control sensor, a disc tray, a display, and all the buttons (Play, Pause, Stop, Tray Open/Close, etc.) you’d expect to find on a disc player. 

On the rear panel are terminals for three types of digital inputs (USB, coaxial, optical) and outputs (RCA, XLR, coaxial), a BNC coaxial connection for an external word clock, a connection for a signal ground wire, and an AC power-cord inlet. 

Esoteric K-03 transport

The K-03 includes Esoteric’s new VRDS-NEO VMK-3.5-10 disc transport, which, the company states, performs substantially better than earlier VRDS models. This transport, which by itself weighs almost ten pounds, incorporates a new driver circuit for precision servo control, a duralumin turntable with “micron-level accuracy,” and a 10mm, solid-steel turntable bridge. Other features include a coreless, three-phase, brushless-spindle motor driven by strong neodymium magnets; a thread feed control; and a shaft-sliding type pickup, by which the laser beam can more consistently read the disc. 

The K-03 has four 32-bit, AK4399 monaural DACs per channel (the K-01 has an incredible eight per channel), sourced from Asahi Kasei Microdevices. Each DAC is mounted on a dedicated analog board and configured for dual-mono operation, with the same layout for each of the K-03’s two channels. 

Power is supplied courtesy two proprietary, large-capacity toroidal transformers. One of these transformers is used to power the DACs and the fully balanced analog circuits, the other to power the digital circuit and transport mechanism. 

As in the more expensive K-01, the K-03 has discrete buffered analog output circuits with high-voltage (±22V) power supplies. These are symmetrically laid out for each of the hot and cold signal lines, for use with XLR connections. The output circuits are switched to parallel configuration for use with RCA connections. 

Inside the K-03’s silvery case is a two-level chassis with five compartments, one for each circuit block, to minimize cross-contamination. At the center is the compartment housing the transport mechanism, which is attached directly to the 5mm-thick steel bottom plate and is supported by three patented, resonant-suppressing feet. 

Two separate audio boards, one for each channel, are mounted near the rear portion of the upper level, close to the rear output terminals. The power circuits and transformers are isolated from the audio board by an internal steel plate, and hang down from the bottom of the board. According to Esoteric, these design features provide for extremely short signal and power paths, thus minimizing the transfer of electromagnetic interference and resonance. 

Esoteric also says that the K-03’s onboard word clock is substantially advanced over past designs: The clock uses a voltage-controlled crystal oscillator (VCXO) with an accuracy of ±0.5 parts per million (ppm); a stabilized power-supply circuit improves the stability of the clock’s operation; and the clock sync signal is directly delivered to the DACs without passing through the phase-locked loop circuit. According to Esoteric, all of this substantially reduces audible jitter. 

For improved performance, the K-03 can be used with an external word clock such as Esoteric’s own G-03X ($5000) or G-0Rb ($20,000). But the company claims that the K-03’s own clock is so good that switching from its ±0.5ppm to the G-03X’s ±0.1ppm will yield only a modest improvement in sound quality. For a serious sonic improvement, Esoteric advises moving up to the G-0Rb, whose rubidium generator, they claim, is accurate to ±0.05 parts per billion

The K-03 has a variety of digital-to-digital conversion functions. These include a mode for upsampling PCM digital to two (88.2 or 96kHz) or four times (176.4 or 192kHz) its original sample rate. The K-03 even upsamples PCM to DSD resolution, which is 2.8224MHz, or 64x the sampling rate of 44.1kHz. 

The K-03 has four types of 32-bit digital filters that provide 8x oversampling for PCM but do not alter SACD’s native bitstream. These consist of two proprietary Finite Impulse Response (FIR) filters, FIR1 and FIR2, and two short-delay filters, S_DLY1 and S_DLY2, all of which can be defeated. The FIR filters are essentially traditional rolloff filters aimed at reducing high-frequency noise. The short-delay filters, which are often called apodizing filters, seek to eliminate pre-echo and ringing effects in the impulse waveform and thus provide sound that is free from digital artifacts. The cutoff frequencies of the FIR1 and S_DLY1 filters vary according to the input sampling frequency; the cutoff frequency of the FIR2 and S_DLY2 filters is about 80kHz. 

For computer audio, the K-03 supports sampling-rate sources of up to 24/192. Of its three transmission modes, one is a standard or normal mode that accepts up to 24/96, and two are high-speed modes -- one adaptive, one asynchronous -- that accept up to 24/192. Each mode is compatible with Apple and Windows operating systems. Also, like PCM, digital music files can be filtered in a variety of ways and/or upsampled to 24/192. There is also a proprietary USB isolator that separates the power and signal paths from the USB input system. According to Esoteric, this protects against electrical interference from noisy external devices such as personal computers. 

Such a level of functionality would seem to be plenty. However, capitalizing on its eight 32-bit DACs, the K-03 also has a 32-bit digital attenuator that permits it to be directly attached to a power amplifier. According to Esoteric, the extra headroom of eight bits over the standard 24 allows for very precise volume control with no reduction of resolution. The gain of the XLR outputs can be adjusted from 0 to 6dB, to accommodate the input sensitivity of the connected amplifier. 

The K-03 comes with an impressively heavy, aluminum-bodied remote control that’s finished in leather on the bottom and sides. In addition to all of the usual source-specific controls, the remote has buttons for volume control and input selection. 

Esoteric specifies the K-03’s analog output as: frequency response, 5Hz-55kHz, -3dB; signal/noise ratio, 115dB; total harmonic distortion, 0.0015% at 1kHz. The K-03 weighs 61.8 pounds and measures 17 1/4"W x 6 3/8"H x 13 1/4"D. 

Setup: plug’n’play (with settings)

The K-03 arrived in a thick, five-sided cardboard cube, which itself was triple-boxed. Removed from its protective cocoon, the K-03 has sleek, jewel-like looks. According to Esoteric, its rounded case eliminates the allegedly “well-known” vibrations caused by top and corner screw designs. Whether or not it does, the K-03’s appearance made every other component in my system look like the homely (albeit less expensive) result of a budget DIY project. 

Playing a CD merely required that I connect a single pair of analog interconnects, plug the K-03 into the wall, place a CD in its transport, and press Play. Easy. But I knew that if I wanted the K-03 to sing, I’d have to experiment with its digital conversion features. 

I first adjusted the upsampling setting. Unlike with some components, I got significantly better sound with the upsampling engaged; the best sound seemed to be with 4x upsampling. Upsampling to DSD resolution produced a sound that was more full bodied but lacked detail, and was syrupy, too smooth, and sounded less natural overall. 

Next, I tried each of the FIR and short-delay filters. S_DLY2 was my favorite -- it was easily the most “analog”-sounding of the bunch, displaying the least amount of glare and digital artifacts. I also liked S_DLY1. The two FIR filters sounded a bit too rich and unnatural, however. 

One thing was clear: The best settings of these conversion features will be those that sound best to the individual user. 

Preparing to play digital music files required a few additional steps. The normal-speed driver installs automatically when you hook up the K-03 to your computer, but the two high-speed drivers need to be downloaded from Esoteric’s website. Before plugging in a USB cable, I downloaded the high-speed drivers, and mostly used the asynchronous USB input for this review. 

A cautionary note: I recommend that you do not change the K-03’s input or even driver selector while it is hooked up to a computer. Doing so often crashed my netbook, prompting an appearance of Microsoft’s infamous blue screen of death. 

Performance: pick your media 

Playing CDs or SACDs, the Esoteric K-03’s sonic hallmarks were impressive: a large, very well-focused soundstage; solid, three-dimensional images; huge amounts of air between instruments; and a very transparent and detailed yet liquid and flowing sound that revealed longer decays of the sounds of cymbal, bass-drum, and piano notes than has any other disc player I’ve had in my system. In fact, the K-03 was so good at reproducing these trailing sounds that it reminded me that pretty much every sound has decay (i.e., continued and deteriorating energy). It further reminded me that, depending on the space in which those sounds are recorded, a great many of them have noticeable reverberation (i.e., the persistence of reflected sound after the output has ceased). As I detail below, the K-03’s ability to reveal these aspects of musical expression was exceptional. 

First up was Ella Fitzgerald and Louis Armstrong’s Ella and Louis (CD, LIM UDH 045), one of several 32-bit-remastered “Red Book” CDs I have from Winston Ma’s First Impression Music. If these discs couldn’t do the K-03 justice, no disc could. Throughout the album, the voices and instruments of Fitzgerald, Armstrong, pianist Oscar Peterson, drummer Buddy Rich, and the rest of the band were laid out across my room in large, solid, three-dimensional images. Armstrong’s trumpet was sweet and velvety smooth, with a pleasing warmth that was no doubt at least partially attributable to the fact that I was using an Audio Research LS27 tube preamp. However, even when I replaced the LS27 with the solid-state NuForce P-9, the trumpet retained an impressive amount of brassiness and texture. 

What Ella and Louis really showcased was the K-03’s startling ability to reproduce the subtle resonances and decays of a human voice. Armstrong’s deep, gravelly voice came through with an astonishingly realistic degree of roughness, and a fuller expression of his throaty articulations than I’m accustomed to hearing from my system. As a big Satchmo fan, I have heard his voice sound better only through significantly more expensive gear. 

Next were “Introduction” and “Violet,” from Niels Thybo, Bo Stief, and Lennart Gruvstedt’s Super Trio, another 32-bit First Impression issue (CD, LIM UHD 047). Here, hard-struck piano keys were extremely weighty and full-bodied, but not congested in the lower frequencies, as they sound through many players. Attacks were crisp, decays unusually sustained. Detail retrieval was so seemingly exhaustive that I could even hear the piano’s hammers striking the strings. Remarkable. 

The K-03’s playback of SACDs was equally sublime. Playing Larry Coryell, Badi Assad, and John Abercrombie’s 3 Guitars (SACD, Chesky SACD289), the K-03 exposed what seemed a never-ending procession of fingers moving over and bending strings. In “Descending Grace,” Assad’s mouth and body percussion were rendered with as much detail and clarity as I’ve ever heard in my listening room. Reverberant echoes were captured to the point that they defined the physical parameters of the church in which this album was recorded. 

A 2L disc of Mozart violin concertos performed by Marianne Thorsen, accompanied by Øyvind Gimse and the Trondheim Soloists (SACD, 2L 2L-038-SACD), was also recorded in a church, and the K-03 really brought home the intimacy of the sound and the small size of the sanctuary. At about 2:15 into the Adagio of Concerto No.5, K.219, the violin fades out, followed by an explosive crash that seemed to emerge from complete silence. 

Having aced SACD playback, the K-03 was now two for two, so I moved on to high-resolution computer audio files, and heard many of the same sonic attributes I’ve already noted. First up was Diana Krall’s Christmas Songs (24/96 FLAC, Verve/HDtracks), an album that, to the bewilderment of my neighbors, I play all year round. Through the K-03, Krall’s voice was smooth and silky, without losing her subtle inflections. Moreover, perhaps due to the precise timing of its DACs, the K-03 effortlessly communicated her pace, rhythm, and timing in “Let It Snow.” Each note seemed to arrive precisely when my body anticipated it. 

The K-03 reproduced Iván Fischer and the Budapest Festival Orchestra’s recording of Beethoven’s Symphony No.7 and works by other composers (24/192 FLAC, Linn Records) with crystalline clarity and remarkable transients. One example of this was the Sinfonia from Rossini’s L’Italiana in Algeri, in which crescendos were bookended by startlingly fast attack and decay transients, the latter interrupted only by lingering and unclouded cymbal decays. The K-03 also beautifully brought out the dense, warmish nature of this remarkable recording, which is markedly different from other interpretations of this classic work. 

The next step was to test-drive the K-03’s digital volume attenuator. The problem with this type of attenuator is that the resolution is reduced by one bit for every 6dB of attenuation. Using a 32-bit chip leaves plenty of room before the loss of resolution degrades the sound of a 16/44.1 CD -- but how would higher resolutions fare? 

Removing the Audio Research LS27 preamp and connecting the K-03 directly to my Bryston 6B SST2 power amp caused a loss of some of the tube magic that mates so well with my otherwise solid-state system. I therefore preferred the sound with the LS27 in the loop. More generally, I don’t think the K-03 can replace a high-end preamp. But no matter the source resolution, the K-03 sounded surprisingly good by itself. All in all, once I’d properly set the gain, this feature worked very well. 

I would be thrilled to live with the K-03 for a very long time. Do I have any caveats? Always. I don’t, for example, think that you’ll see a wave of vinyl enthusiasts trading in their VPI and SME turntables for a K-03. Even with the S_DLY2 setting activated, which I found sounded most analog-like, the K-03 still lacked the inviting warmth and richness of the very best analog gear. On the other hand, the K-03 offers a dynamic range, consistency of speed, and quietness that vinyl and analog tape enthusiasts can only dream of. Also, in order to get that analog-like richness, you’ll have to spend a lot more money, and perhaps even move on to something like the K-01. 

Also, with respect to components that contain their own DACs, one must consider the rapid pace at which digital technology evolves. With the K-03, as better DACs are introduced -- and they will be -- you’ll find yourself replacing not only your DAC but your disc player as well: a potentially expensive proposition. However, few of those future DACs will be made to the performance-enhancing standards of the K-03. This is not the type of model that will be redesigned every two years. Too much thought and effort has gone into it. 

Also, there are substantial savings in money and rack space to be obtained by having only a single component with one set of parts -- signal and power connectors, transformers, etc. -- instead of the multiple sets required by separates. In fact, to match the K-03’s build quality and performance with separates, you’d likely have to spend close to twice the K-03’s $13,000 asking price. 

Comparison: yours may have a volume control, but mine plays Blu-ray!

I’m currently using a Tube Research-modified Marantz UD9400 universal disc player (approximately $8000 as modified) as a transport. For a DAC I use the Audio Research DAC8 ($4995). These and the Esoteric K-03 don’t make for a perfectly level comparison. (Good luck in finding a pairing that would be perfect in this way.) The K-03 plays CDs, SACDs, and computer audio files, and has a built-in preamp, while the UD9004 plays CDs, SACDs, DVD-Video, DVD-Audio, and Blu-rays. The DAC8 serves only as a DAC, and does not read SACD bitstreams. It does, however, have a generous number of inputs, including RCA, which permits it to be connected to a CD player. 

Pitting the K-03 directly against the less expensive modified UD9004 left the latter pleading nolo contendere. As good as the UD9004 sounds, the K-03 proved the decidedly better performer with both CDs and SACDs. The same was true with the UD9400-DAC8 combo, which, while significantly upping the ante (less veiled, more weighty and transparent, with larger, more solid images), still couldn’t match the K-03’s performance. 

Finally, for computer audio files, I pitted the K-03 against the DAC8. This was certainly a more interesting comparison, but still grossly unfair in light of the price difference. Playing the DAC8 after it had been out of my system for several months made me realize why I’d bought it in the first place -- for the money, it’s tough to beat. 

To get a wide taste of what these DACS could do, I turned to Chesky’s The Ultimate Demonstration Disc, Volume 2 (24/96 FLAC, Chesky/HDtracks). Throughout these and other digital files I played, the K-03 displayed a slightly more laid-back sound than the DAC8. The K-03 also brought its “A” game along, with better air, transparency, image solidity, detail, soundstage size, and finesse. This was impressive -- ARC gear in general, and the DAC8 in particular, are known for these latter traits. 

However, it was the decay-and-reverberation thing that I kept coming back to. The cymbal decays in “Imagine,” from the Chesky demo disc, seemed to endlessly loiter until arrested only by the presence of the next sound, whether a drum stroke or guitar or piano note. In the third movement of Bassoon Concerto, the solo instrument brimmed with resonant textures. The DAC8 did all of this well, but it couldn’t compete with the K-03, which simply did all of it better -- as it should, in light of its much higher price. 

It wasn’t difficult to conclude that the Esoteric K-03 and the Audio Research DAC8 bring to the table two of the best DACs currently available. For $8000 more than the DAC8, however, the K-03 also offers CD and SACD playback, volume attenuation, better sound, and those digital conversion features. The K-03 also has a build quality and high-end aesthetic offered by very few, if any, other models costing under $10,000, and even by few that cost more. 


To hell with the audiophile in-crowd. I’m giving the Esoteric K-03 a Reviewers’ Choice award, no ifs, ands, or buts. It’s the Swiss Army Knife of high-end audio. In fact, it does so many things so well that if Esoteric told me that an amplifier, a pair of tower speakers, and 50 jazz CDs were jammed into its box, I almost wouldn’t be surprised. More important, the K-03 does all of these things at an uncommon level of performance. 

If you’re like me and have embraced the world of computer audio but aren’t yet ready to mothball your collection of shiny 5” discs, this one-box player may be just what you’re looking for. 

. . . Howard Kneller

Associated Equipment 

  • Amplifier -- Bryston 6B SST2
  • Preamplifiers -- Audio Research LS27, NuForce P-9
  • Sources -- Marantz UD9004 universal Blu-ray player modified by Tube Research Labs, Audio Research DAC8
  • Interconnects -- Synergistic Research Tesla Apex, Precision Reference, Synergistic Research Galileo MPCs (on all signal cables and power cords)
  • Digital cable -- Synergistic Research Tricon USB
  • Speaker cables -- Synergistic Research Tesla Apex
  • Power cords -- Synergistic Research Tesla Hologram A (amplifier) and D (source), Precision AC (speakers and Powercell 4 power conditioner), Precision AC SE (Powercell 10SE power conditioner), T2 (preamplifier)
  • Power conditioning and distribution -- Synergistic Research Powercell 10SE (power and analog) daisy-chained to Powercell 4 (digital), Synergistic Research QLS 6 and 9, DIY parallel filter
  • Isolation devices -- Silent Running Audio VRfp Isobases, Synergistic Research MiGs, Mapleshade Heavy Hats, DIY amp stands
  • Misc. -- Synergistic Research Galileo Universal interconnect and speaker-cable cells

Esoteric K-03 SACD/CD Player/DAC
Price: $13,000 USD.
Warranty: Two years parts and labor (three years with return of product registration form). 

Esoteric Division
TEAC America, Inc.
7733 Telegraph Road
Montebello, CA 90640
Phone: (323) 726-0303
Fax: (323) 727-7650