Holo Spring DAC Level 1

"If it measures good and sounds bad—it’s bad. If it measures bad and sounds good, you’ve measured the wrong thing." —Daniel R. von Recklinghausen, Chief Engineer, H.H. Scott.

The main thing I’ve learned after an adulthood of listening to recorded music is that we still don’t really understand what makes it fun. What I mean is the factors that make music reproduction emotionally engaging (as opposed to accurate sounding) remain, to a significant extent, a mystery. This is especially true of digital. Which makes sense—the phonograph disk has been around since Emile Berliner introduced it in 1889. Digital encoding arrived nearly a century later, and after three-decades-and-change we’re still getting our heads around how to make it sound like music.

Let’s not be shy about the fact that this pursuit has taken us down some blind alleys. This is probably as good a time as any to admit that the promise of high-resolution formats as a transformational force in musical enjoyment has been, to put it kindly, overblown. I’m not suggesting that hi-rez doesn’t sound different. But does anyone still believe that playing "Crimson and Clover" sampled at 768,000 kHz will make you feel like Joan Jett is stomping her Cuban heel on your coffee table?

Then there are uncomfortable reminders from the past that suggest that digital’s latest crop of innovations may not be bringing us closer to our musical goals. As it happens, some listeners—including my friend Herb Reichert, owner of one of this planet’s most astute musical brains—prefer the sound of plain old CD-resolution files to high-rez. Come to think of it, so do I.

And consider the crop of CD players and DACs from the distant past (circa the 1990s) that, according to some audiophiles, still play music as well as anything that came after. One of the most popular among these is the Sonic Frontiers SFD-2, a digital-to-analog converter that cost $4650 in 1993 money, decoded nothing but redbook files and relied on the Ultra Analog D20400A, a device once ubiquitous among top-shelf gear from the likes of Stax, Spectral and Mark Levinson. The D20400A was not an integrated chip but a 20-bit ladder DAC that utilized thin-film resistor networks to make sense of the digital data stream.

The ladder DAC (also known as a R-2R network) still powers some of the most natural-sounding gear around. Its biggest drawback is expense; the dozens and sometimes hundreds of high-precision resistors it requires can cost as much as a minor cosmetic-surgery procedure. But its reputation for "non-digital" sound has kept the topology from going away. Audiostream editor Michael Lavorgna liked the totaldac d1-six so much that he spent his own personal money on it, though the €12,400 price tag nearly gave him an emotional hernia. Other gear that employs ladder DACs—from MSB, Light Harmonic, Aqua and a handful of others—isn’t what one might describe as eminently affordable, either.

Which brings us to an R-2R fan named Jeff Zhu—a 40-year-old audio engineer from Suzhou, China—who came up with a scheme he calls "linear compensation." In simplest terms, Zhu adds a second resistor network that performs an error-correction function, allowing all those high-precision resistors to be swapped out for relatively inexpensive ones. His decoder—named the Holo Spring—recently became something of an online hit, celebrated on the audio forums as a totaldac for the masses. This sounded interesting.

And so, several months ago, Kitsune Hi-Fi’s Tim Connor—Zhu’s Lynwood, Washington-based collaborator and distributor—sent Michael Lavorgna and me a pair of Spring DACs. Michael received the tricked-out Level 3 while I opted for the Level 1 ($1,499), i.e. the basic model. (For information about the differences between models and other technical small print, see Michael’s review or the Kitsune Hi-Fi website.) We planned to listen to our respective Springs for a few months and then compare them side-by-side.

Due to scheduling problems, the side-by-side taste test didn’t happen. But I did spend several memorable months with the Spring, which is what I’m getting around to telling you about presently. In the interest of forward momentum, I’ll skip describing the functions of the Spring’s plain-and-sturdy pizza-box-like chassis and proceed to the business end of this article.

Over the years I’ve owned some shitty digital. Not only because I’m a NYC-based working writer of commensurate means, but because digital seemed like a poor place to put my money. Now and then, when I heard what lots of money could buy at friends’ homes and at audio retailers, I wasn’t particularly tempted. Because even the best digital had what I came to think of as a look-but-don’t-touch quality. It’s as if you were a shabbily-dressed tourist walking through a store that displayed beautiful, expensive objects in locked glass cases. You could see them but could never handle them. Not a single digital component allowed me to connect to my music, to physically revel in it, something I could dependably pull off with even a modest turntable. (Later, I was surprised and weirdly delighted to discover that Michael Lavorgna used a similar metaphor—a sheet of glass separating the listener from the music—when describing his experience with most digital playback.)

After I took the (already broken-in) Spring out of its shipping carton and plugged it in, I didn’t hear anything that suggested it would play music much differently. My files sounded decent if a little flat. I hadn’t yet discovered that the Spring requires more than a dozen hours of being continually on (presumably to reach thermal stability) to sound its best. But as the music played in the background hour after hour, something about it began to nag at me. The Chinese DAC’s sound was reminding me of something, and it took me a while to realize that the something was my Garrard 301 turntable.

Things were sounding better and better. Then, about eight hours after I turned on the Spring, Roon Radio sent it Scott Walker’s "Copenhagen," from 1969’s wondrous Scott 3. Surrounded by a violin tremolo and bells in a huge sound field, Walker sang the lines "Copenhagen, you’re the end/Gone and made me a child again" with so much tactility and color that I might’ve actually gasped in surprise. It sounded wonderful, but more importantly nothing was standing between me and the music. The glass barrier was gone.

I realize that I’m describing this experience in irritatingly vague terms, but there’s little in the sonic vocabulary that I can hitch it to. To get a better handle on what I was hearing, I compared the Spring to my similarly priced Ayre Codex. The differences between them, in sonic terms, were not terribly meaningful. The Spring had a slightly larger soundstage; the Codex was a little more refined, making the Spring sound just a bit shouty. But in musical terms the difference was immense—most of the time the Spring allowed me to emotionally connect with my music, while the Codex, for all of its exceptional sound, did not.

I did all my listening in Spring’s non-oversampling mode (the other modes, which involve an AKM chip-based oversampler, are best left unmentioned). I also found that the Spring did an equally fine job with every format it played back, including hi-rez PCM and DSD. It did emit some occasional burps and farts when switching sampling rates and formats, but these weren’t as offensive as I’d heard with other gear. Connor also sent me a Singxer SU-1 D-to-D converter, suggesting that things could be improved further by adding it between the Sonore MicroRendu and the DAC, connected to the Spring via a short HDMI cable. I did hear an improvement with the SU-1 in place, but found it to be, in absolute terms, quite small.

One caveat. I was able to coax this level of performance out of the Spring only after optimizing things upstream of the DAC to an extent that, until recently, would’ve struck me as excessively fussy and even kludgy. In my system, files traveled from an external hard drive attached to a Small Green Computer SonicTransporter i5 running Roon Core through a playback chain that included a router, two opto-isolators and either a Sonore MicroRendu (powered by Vinnie Rossi’s Mini PURE-DC-4-EVR power supply) or a SOtM SMS-200 (powered by SOtM’s mBPS-d2s power supply), all lashed together with plenty of fancy Ethernet, USB and fiber-optic cable. With the SOtM unit in place, I got better results by adding an Uptone Audio USB Regen (with the Rossi PS) between it and the Spring. Holy crap! I'd plugged in nine devices just to get my file to the DAC. But I had to admit that the sound and musical connection this Rube Goldberg playback chain provided was immensely better than what was possible with a laptop or even most dedicated servers connected directly to the DAC. And to my eternal irritation, changing any bit in this playback chain made an easily discernible difference. All this leads me to the observation that the hours of tweakiness required to set up a good turntable are now dwarfed by the effort required to set up a good digital playback system—digital has surpassed analog in sheer fussiness!

But wait, there’s more. After returning the Spring to Tim Connor, I realized that I missed it enough to want to buy it. Which I did, at full retail price. Actually I bought the slightly more expensive Spring Level 2. Connor suggested it was the value-for-money sweet spot in the range, and who was I to disagree. Frustratingly, I didn’t get a chance to compare the L1 and L2 Springs side-by-side either, but having spent many hours listening to both, I can share two observations. 1) The audible differences between them are slight. But if I had to define them, I’d say that 2) the L2 gets rid of some tonal grayness I heard with the L1, and sounds a little warmer and more colorful.

For me, the Holo Spring proved to be a transformational product and my first experience with fully-immersive digital. I haven’t heard the latest offerings from totaldac and dCS, which are reputed to do the flesh-and-blood thing even better than the Spring, but then I couldn’t afford to own either. Jeff Zhu’s ingenious and affordable converter opens the door to this experience for many more listeners. Now that's an actual innovation.

snoopy's picture

And the price is ?

thx for the review

Michael Lavorgna's picture
The price for the Level 1 DAC is $1499. I've added this to the review.
volvic's picture

I don't come here often as I am more into analogue and think my lowly MacBook/Glyph HD, does a decent job of playing my 16 bit CD's through a Moon 300DAC and Stello U3. But I am glad I came and enjoyed this great, honest and fresh review. Well done! and thanks for giving me a break from a dreary work day!

ednaz's picture

I'm really curious about what it is about ladder DACs that makes them sound more immediate, more alive, and gets the listener on the right side of the pane of glass. I'm about to allow myself an upgrade to an Exasound e22, and this review, plus the one of the upgraded Holo, really has me thinking.

It's so unfortunate that our e-commerce world has made comparative listening so hard.

GarkM's picture

Thank you for a great review and for describing so well the problem I've heard with (affordable) digital playback. I'm hoping the price and device count for an immersive experience will come down even more in the near future.

Anton's picture

I feel so old!

I can give a partial answer to the "digital problem."

It's similar to the drum machine problem. I'm on a phone, so short typings; but the topic is fascinating and may require products of natural fermentation and lively tunes to hash out!

That was a great review.

kukur9's picture

Digital has become just as fussy as analog, and just if not more expensive to test the possibilities. After putting the mRendu and the corresponding power supplies to the test, someone (of course) suggested even the DC cable could add weight and transparency. They were right. Then I could hear the deficiencies in my other, heretofore perfectly acceptable interconnect. And so it went, even into which input was best on my DAC, even into my computer networking cables/gear. Not all changes were positive–unfortunately some were downright awful. But almost all sonic changes were (gasp) clearly audible, particularly in the bass and how it integrated (or didn't) with the lower mids. Oh, and treble extension too.

In the end (read: bank account/budget limit), the system sound is glorious. It compares more than well against my dealer's bigger buck gear, and I know my ears (still) work.

I know what these different DACs sound like in part due to reviews like this one, and in part due to listening for the ineffable character revealed by all these digital parts. In my system, I feel the whole exceeds the sum of the bits.

Thanks for sharing your experience, Alex.

R1200CL's picture

I think the Holo Spring DAC doesn't have volume control.
Correct ?

I was tinkering adding the DAC in front at a very good preamp or DAC with proper volume control would be essential.
Am I wrong?

Also, one day try a modified SU-1 and power it with an Uptone LPS-1 :-)