Holo Audio L3 KTE May DAC Review
Mark Gusew samples a unique digital-to-analogue converter…
L3 KTE May DAC
When it comes to digital-to-analogue conversion, there are a number of competing technologies available. Some high-end manufacturers are not content with off-the-shelf DAC chip offerings from the likes of ESS Technology, AKM, Wolfson, Texas Instruments, et al., and instead prefer to use their own proprietary circuits. Holo Audio is one such example, a company that makes unique resistive ladder (R2R) style converters and utilises them in its range of DACs. Here we review the flagship May Level 3 KTE, which sells in North America for $5,598.
The May is an all-out assault on building arguably the quietest and most linear DAC available. The power supply is housed in a separate chassis to the DAC and connected with a high-grade umbilical cable. It is a dual-mono design with a pair of special custom-made 100VA dual O-type audio transformers, which feature high-grade 6N flat (not round) copper wire. This design is different to the more commonly used toroidal transformer and is said to have a more uniform magnetic field distribution and lower leakage due to the shape. Which, according to Holo Audio, is one of the key ingredients to its low noise floor.
The DAC chassis is also a dual mono layout with distinct digital conversion boards on either side of a central input circuit board; all sections are screened off with thick metal dividers. All the usual inputs are catered for, including USB, optical, AES, both S/PDIF RCA and BNC, with an additional two I2S inputs via HDMI. As there is currently no official standard for I2S, Holo Audio has user-configurable pinouts so that you can connect a variety of sources. The USB board received a lot of attention and uses the high-speed XMOS xu208 controller chip with custom firmware to improve the USB Eye Pattern and reduce latency and jitter to extremely low levels, it is said. The USB and I2S interfaces natively support speeds up to DSD1024 and 1.536MHz PCM.
Getting back to the R2R DAC modules, I asked Jeff Zhu – the engineer behind Holo Audio – where the inspiration came from for building his bespoke DACs. He said:
I'm an audiophile, but was not involved with the audio industry until recently. I was developing test equipment which is not for an audio product but for an industrial DAC. Then I found the problem of R2R glitches that bring trouble to the whole design. I got an idea of how to solve the problem and finally succeeded. Then I realised this technique can also be used for an audio DAC. I didn't expect it to be a business. I just developed it for fun. But soon some audiophiles wanted my DIY DAC. So I said “why not”, at least this can cover my design costs. That DAC is based on the Burr Brown PCM1704. Soon I'm not satisfied with the old PCM1704 chip, and think I can do better with a discrete design…
The KTE May DAC uses two hand-selected DAC modules with fitted copper shield covers, along with Jeff's unique linear compensation technology that's said to solve the accuracy errors caused by resistor tolerances. With the compensation applied, the DAC reaches an incredible claimed 0.00005% tolerance accuracy. Holo Audio employs a proprietary PLL+FIFO technology that allows the DAC to be almost immune to front end jitter, it is claimed. Also used is an audio-grade, ultra-low phase noise Crystek CVHD-957 Voltage Controlled Crystal Oscillator. The oversampling is switchable but has been designed to sound best with no oversampling selected. For the sake of brevity, I've only briefly skimmed some of the challenges that have been tackled by Jeff in the May's creation, but needless to say the engineering is impressive.
This DAC is unusual because there are three levels of tune available to purchasers. Jeff explained to me that the standard version which he designed is Level 2. In order to meet a wider price range and demand, Level 1 is a cost-reduced version based on Level 2. The May Level 3 KTE (Kitsune Tuned Edition) tested here has been developed by Kitsune HiFi in the USA with several small but important upgrades by using better components to “squeeze out the potential of the design”. The sonic improvements make the Level 3 KTE the highest performing DAC made by Holo Audio.
The twin chassis design is striking, with the use of copper on the sides of the chassis, the feet and the buttons of the supplied remote control and the front panel. A lovely bright and legible display completes the front panel, using white characters on a black background that are readable from across the room. The panels are CNC machined to very high tolerances and fit together with precision. There's a choice of balanced RCA and unbalanced XLR outputs, with the unbalanced preferred.
This is an insightful and rewarding source component that's a joy to listen to. I primarily listened in NOS (Non OverSampling) mode, where it's amazing how quiet the noise floor is. This provides the perfect backdrop for its smooth, rich and textured sound. It creates a holographic image of the musical performance, with great separation between instruments and vocals. Dare I say that it portrays some of analogue's best qualities?
For example, listening to Yellow Brick Road by Angus & Julia Stone demonstrated a nicely balanced sound that was neither soft nor hard, just right. The May delivers the feel of a recording in a very smooth and refined way. Tonally it is spot-on, with a very wide frequency range, seemingly without limits and excellent evenness. This is a characteristic common in R2R designs that I have previously heard.
The bass and drums on Tin Pan Alley by Stevie Ray Vaughan & Double Trouble were very well defined, each with its tone and texture intact and with excellent deep bass extension and impact. Cymbal work sounded delicate, airy and with just the right amount of bite. The sound through the May KTE was never harsh, clinical or overly bright. Buena Vista Social Club's Chan Chan was as open and transparent as I've ever heard it, without a clinical or overly etched sound that drew attention to itself. Instead, I heard natural sounding instruments playing in different places on the stage.
Get Lucky by Daft Punk feat. Pharrell Williams showcased this DAC's fine timing. Bass guitar was reproduced with great speed and attack, syncopating perfectly with the drums and guitar. Kraftwerk's Showroom Dummies was also a real foot-tapper, the spaces between the beats beautifully judged, like a laser light quickly and accurately switching on and off again. The sheer energy and dynamics of Electrified by Boris Blank wasn't blunted in any way, sounding exciting and cohesive at any volume setting.
Listening to the excellent remastered Qobuz 192/24 version of Maybe Your Baby by Stevie Wonder, I was struck by the dynamics, energy and punch of the Clavinet organ and Moog bass. This 1972 recording came alive when using the May DAC. The loudspeakers disappeared, and I felt enveloped in a sound bubble that wrapped right around the front wall and halfway into the room.
Not all recordings presented such a wide soundstage, of course, but with an expansive sounding track like At the Purchaser's Option by Rhiannon Giddens, there was a lovely full soundstage that extended a little past my speaker boundaries and had excellent stage depth.
The USB input sounded particularly good when fed by my Melco N1Z digital transport. I loved seeing the panel display indicate the correct sampling resolution as I went through my playlist. One item of note was that a change in sampling rate brought with it a four second delay, with the sound muted during that time. This would mean that I often missed the first couple of seconds of the start of a new track, which is somewhat frustrating.
The May DAC sounded more detailed, open, natural, unforced and relaxed in NOS mode, so little wonder that it's Holo Audio's default setting. Listening to the three other oversampling modes seemed to lessen the tangible specialness and deflated the imaging, dynamics and air around the performers. At least the option is provided.
I also had the cheaper Holo Audio Spring 3 Level 3 KTE DAC (single chassis) as a back-to-back comparison with the May KTE, and was mighty impressed with its relative performance. They share the family traits of smooth neutrality and openness, with both sounding almost tonally identical, but the May has been created for those with higher resolution systems with better quality source components and cables. The May DAC is noticeably quieter, which didn't seem possible, has more top and bottom extension, with a wider and deeper soundstage. It has more special sauce and could be better value depending on your end game.
The Holo Audio KTE May DAC is an impressive sounding digital converter that beguiles the listener the longer that it is listened to. When teamed up with other high definition components, it's capable of providing incredible levels of detail and insight within a recording, and continually rewards.
Jeff Zhu told me that he never set out to create a large, complex company that would be tiresome to manage. As an engineer, he just wants to develop interesting products that sound incredible. So Holo Audio uses a non-traditional distribution method around the world and has limited sales and marketing resources – so consumers are paying mostly for the design and quality of the products. That philosophy may attract consumers or make them cautious.
There isn't one single aspect of this design's performance that particularly impresses; instead, you soon realise that it's a sum of its parts with a natural, smooth and unforced delivery. I reckon the potentially better performance/price ratio of the May Level 2 is seductive – but many will love this. Highly recommended, then.
Starting his first audio consultancy business in the early ’80s whilst also working professionally in the electronics industry, Mark now splits his time between professional reviewing and AV consultancy.
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