exaSound Delta Music Server

A digital front end comprises several elements: data storage, library management, program control, signal distribution, signal conditioning, and digital-to-analog conversion plus all the necessary interconnections. All this can be contained in a convenient single box, or it can be distributed.

Over the years I've been engaged with file playback, I've come to prefer a distributed approach, with three elements. The first is a NAS (or other medium) that stores the music data and puts it out when requested. The second is a computer that runs the library-management and control software that (among other things) coordinates the transfer of music data, and, when called upon, handles upsampling and DSP. The third and final element is an endpoint that contains a DAC.

Of these, the first is uninteresting: It can be anything from a flash drive to a multidisc NAS. The only real requirements are that it hold your whole library and deliver it to the rest of the system fast enough. The last one is an audio component, and different users will demand different things of it: how it connects, what formats and resolutions it supports, and how many channels. Also important, of course, are how it sounds and what it costs.

In between these two is the music computer.

A music computer can take many forms. It can be a smartphone, a single-board computer, a generic or customized PC, or a dedicated music machine. How one chooses depends on personal taste and on the demands of the task. Even the simplest and most portable can easily stream two channels in MP3 or CD quality. But once you start piling on the computational challenges—higher resolutions, decoding lossless compression codecs, upsampling and downsampling, electronic crossovers, DSP, and multiple channels—a bigger, faster processor becomes necessary in a hurry.

What's needed, then—especially for multichannel systems—is a computer with a powerful processing engine, chosen with attention to keeping noise low (both electrical and acoustical) and with suitable input/output connections.

The Delta
The exaSound Delta ($3000 without storage) fits the bill. It runs one of today's most powerful PC CPUs, the Intel i9-9900, and it's passively cooled: no fans, no noise. It is housed in a snazzy enclosure that resembles a miniature industrial cooling tower. It runs exaSound's custom Linux operating system and boots up running Roon. It uses one SSD to run the OS and Roon and, optionally, another for file storage to form a digital source. SSDs store data without moving parts or noise. Plus, storage is cheap.

I connected the Delta to my LAN by Ethernet cable (footnote 2) and pointed Roon to my NAS library. I connected the Delta to the exaSound s88 DAC and to my Okto dac8 PRO DACs by USB. The Delta recognized the s88 as a Roon RAAT via LAN. That's it; you're ready to play music.


Just as with any other Roon core device, you can control the Delta with a smartphone, tablet, laptop—any device that can run a version of Roon's Remote software. But exaSound also offers a cute touch-screen accessory with a nice display and playback controls. If the Delta is connected to an exaSound DAC by the local USB connection (rather than as a Roon RAAT), the display will show the cover art and metadata for the current track, and the volume controls on the touchscreen control the attached DAC.

However you set it up, the integration of Roon with Delta is as tight and organic as it is with Roon's own Nucleus +—but the Delta has more processing power. Try playing multichannel DSD256 and then turn on upsampling, or DSP (for room eq or active filtering)—or both—and you'll quickly see which one has the chops. Both get pushed, but the Delta copes while the Nucleus+ hits a wall, as I reported in my Nucleus+ review in Music in the Round #96. True, the Delta costs more and is much larger because the passive cooling necessary for the faster, hotter CPU takes up more space. I love the design and like to look at it, but you can put it anywhere; the only requirements are power and hard-wired access to your LAN.

The Delta is about 10% more powerful than my Baetis Prodigy X4i-KR, which runs a 10th generation i7. In practice, they both performed superbly, allowing me to fully enjoy the music in its recorded resolution or, if I chose, upsampled or bass-managed or with other DSP options. Both had limits in how much processing they could perform. In terms of sound quality, I could hear no differences between these music computers; any distinctions noted during listening were associated with the DACs and their settings.


Does this mean that all servers—all data sources—sound the same? Unless they put noise on their physical outputs, cannot handle the load, manipulate the data in some new way, or are simply faulty, the data they output should be identical. On the other hand, studies have found small differences in the DAC output when S/PDIF data sources are used—so, strictly speaking, bits are not bits. The measured differences, though, are probably too small to be audible and USB/LAN sources have not yet been shown to be similarly affected.

Summing Up
The Delta Music Server is the most capable server I have used, but it is far from the most expensive. The base price is $3000, in silver or black. The addition of a 1TB SSD for local storage adds $150, and the 7" touch-screen adds $280. If you are capable and motivated, perhaps you'd prefer to build something like this yourself; you probably could do it for less money. The only caveat I can think of is that it is dedicated to Roon and will not support other software. The Delta is, in my opinion, what a Roon server should be.

Footnote 1: exaSound Audio Design, 3219 Yonge St., Suite 354, Toronto, Ontario Canada M4N 3S1. Web: exasound.com.

Footnote 2: Although the Delta does not have Wi-Fi, connecting it to your LAN via Ethernet cable and a router/switch gives it access to all the Wi-Fi devices on your LAN. This restriction helps insure that the datastream from your storage device to the Delta is uncompromised.