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Happy New Year! Last time, I touched on the differing viewpoints regarding playback of digital audio, based on my impressions of discussions between a number of personalities in high-end audio. I want to continue with a brief survey of my own digital setup, and how my experimentation with various streamer/server setups, digital cables, and DACs has informed my approach to digital audio. My current digital setup is eons beyond the single-box, limited-capability streamers from High Resolution Technologies (HRT) that provided my earliest forays into digital playback. At the time, they were great but also very limited in scope, and only capable of streaming 16-bit PCM files—thinking back, they were really much more like digital toys.

My Digital System

The current complement of digital gear in my audio system includes a dual-box configuration streamer/server/music player from Croatian manufacturer Euphony Audio. It includes a separate server/file organizer, the Euphony Summus, as well as a music player/streamer, the Euphony Endpoint. Both are glorified Intel NUC units inside Akasa cases, running a proprietary, highly customized and streamlined Linux operating system that’s been optimized for music playback. The system features a beautiful graphical user interface (GUI) and is extremely user-friendly, and the latest version of the OS has features that allow an even higher degree of configuration and customization of your music playback. I love the look and sound quality so very much, to the point I walked away from my Roon subscription two years ago.

The system includes a DAC from manufacturer Gustard, its X26 Pro delta-sigma unit that provides a level of features, connectability, performance, and musicality that easily positions it in the same company as much more expensive DAC designs. Its build quality and top-rank parts selection (including a pair of top-of-the-line ESS ES9038Pro DAC chips) provides a superb foundation for musical performance; it excels with both PCM and DSD sources. It works in tandem with a Gustard C18 Constant Temperature OCXO 10MHz master clock. “OCXO” stands for Oven Controlled Crystal Oscillator; the “oven” heats the clock, providing more consistently stable signal oscillation than typically found in most internal DAC clocks. The C18 in the playback chain results in greater retrieval of fine detail, improved pacing and flow of the music, a more defined and palpable soundstage, and a greater sensation of realism in recorded performances. The C18 is connected to the X26 Pro with a BNC digital cable, which offers another style of proprietary digital connection between source equipment.

I’ve also acquired a Topping E70 Velvet DAC; Topping is another manufacturer that produces products that punch well above their weight. My contact at Euphony Audio, Dalibor Kasac, reached out about the E70 Velvet, insisting that I should have a listen; he guaranteed I’d like what I heard. The E70 Velvet is also a delta-sigma DAC that features one of the first implementations of the new series of AKM chips that have just reappeared on the market following the disastrous fire that nearly wiped them out a few years ago. AKM’s “Velvetsound” configuration implements a sequence of two chips to accomplish the delta-sigma modulation and digital-to-analog conversion. What makes the big difference in AKM’s implementation is that by separating the processes to individual chips, there’s a clear path for native DSD signals to proceed through the delta-sigma modulation to the digital-to-analog conversion stages without combining native DSD signals with PCM signals. That essentially means that with DSD playback, you’re listening to a 1-bit DSD-direct DAC. The resultant sound quality of DSD files at any level of playback through the E70 Velvet is unbelievably good!

Capabilities of Digital Cables can Vary Greatly

Most current DACs and streamers can play any file type and bit-and-sample rate, whether PCM or DSD, and offer digital connection choices well beyond the typical coaxial or USB input. My Euphony dual-box system and Gustard DAC both feature the choice of using an i2s digital connection, which provides a greatly enhanced range of file compatibilities, and offers more transparent digital sound quality than that of the more utilitarian, potentially-noisier USB connection. The cable used in the connection between your streamer and DAC makes a definite difference; the objectivists would have you believe that the typical throwaway USB cable supplied by most manufacturers with their DACs are perfectly capable of rendering superb digital sound quality. After all, bits are bits, right? Upon receiving the Topping E70 Velvet DAC—which implements a USB input from my Euphony stack—I investigated upgrading my USB digital cable and settled on a $70 Oyaide Neo D+ USB cable that has gotten raves from The Absolute Sound and users from every corner of the Web. After a hundred hours of burn-in, I’m convinced it’s the best sounding USB cable out there—especially for the relative pittance it costs.

Of course, there’s the choice of using the i2s digital connection, if your equipment allows for it. Most current i2S cable implementations use an HDMI-type cable and connector, though i2s and HDMI do not actually share any common technologies. I’m convinced the i2s connection is a superior one, but it also requires the need for a first-rate cable; after a great deal of research on the matter, I found the cable I’d been looking for from German manufacturer Sommer. The Sommer Excelsior BlueWater EBH4 ($200) gets high marks from a number of high-end DAC manufacturers; it appears to be the high-end cable of choice, and I went to great strides to get one. I’ve had it in the system for over a month now, and with several weeks of burn-in, it’s elevated my digital system performance significantly.

The other digital cable in my system is the Audio Art Cable Statement BNC ($476) that connects the Gustard DAC and clock units. I was keen to add an external oven-controlled, constant-temperature clock to my system, but the Gustard C18 didn’t at first seem to make the kind of difference in sound quality I was expecting, especially with its throwaway stock BNC cable. Upgrading to the Statement BNC cable snapped everything into focus, and allowed the DAC and clock combination to better communicate with each other, greatly enhancing the musicality of my digital rig.

Is File Compression an Issue?

Another segment of the whole bits are bits ethos involves the files you stream from a streaming service, which likely began life as analogue files that were converted to digital, then ripped as FLAC, which is just a different, more stream-friendly flavour of PCM digital. Most ripping programs—I use dBPoweramp—default to compressing PCM files to FLAC by about 50%. I’ve downloaded digital files from Qobuz and HD Tracks that were compressed by as much as 80%! The bits are bits crowd tells us that FLACs, when processed by DACs, don’t suffer from the expansion they’re subjected to when going from their compressed state to the uncompressed one that plays on your stereo. The guys at Euphony Audio (and trust me, they’re total geeks!) tell me that when you play compressed FLACs, a transfer function takes place during the expansion of the file that negatively impacts the sound quality, and that transfer function doesn’t happen with uncompressed FLAC files. Streaming services compress their files because it makes the file size significantly smaller, and it’s easier to store and transmit those files across a network. But in an age where storage is so cheap, why not have all your stored digital music files uncompressed on your server? I have ripped the PCM portion of my entire digital music server to uncompressed FLACs, and have also used dBPoweramp to convert any digital PCM downloads on my server to uncompressed files. There’s no need to do this with DSD files—they’re always uncompressed.

The objectivists will tell you that you can’t possibly hear a difference between compressed files and uncompressed files streamed across a network. But there’s a long list of audiophiles who have assured me that they can hear a difference between the compressed files played over a streaming service, compared to the same files uncompressed and downloaded to their servers. I hear this time and again, so it’s not just me saying it out there in the wilderness! My Euphony server also buffers all digital music files to RAM (computer memory) prior to playback, where the path from the SSD storage to the processor is completely removed. The file then plays directly from RAM to the Intel processor, which results in a solid uptick in sound quality. YMMV, but five years of the Euphony experience has convinced me that buffering to RAM is essential to perfect digital playback from both PCM and DSD sources.

I have more ground to cover on all this, and will talk more in depth about differences in digital cables next time around, including differences between USB, i2S, and BNC digital cables. Till then, happy listening!