World Premiere Review!
I've been late to a number of parties. I had such a great vinyl collection I was no early adopter of digital audio. When I did dip my toes in it was a Denon 3520 in around 1990, eight years after the launch of the CD, and I continued to favor my Linn Sondek LP12 until I reviewed and bought a very musical CD player, the Meridian G08 in 2004 (as reviewed here). I've progressed through a series of upgrades since then, culminating in the EMM Labs XDS1 which I use as a transport and the EMM Labs DV2, which is my DAC and volume control, eliminating the need for a preamp in my all-digital system. Now my walls hold two giant racks filled with CDs and SACDs and I have felt no great need to jump on the streaming or digital server bandwagons.
As a reviewer, I have dipped my toes into the streaming water a few times and I have built up quite a collection of digital music files on my computer. I even have a NAIM UnitiServe to feed a UnitiQute in a second system, but I haven't used it since I moved house a couple of years back, and now the unit seems to have expired. I have enjoyed using TIDAL through the remarkable KEF LSX active speakers but was not enamored of the user interface.
But the market has moved and out of a maze of competing standards, one service has come to dominate, and that is Roon. Roon is everywhere these days. My DV2 DAC supports it, your DAC likely supports it or will soon, and I'm pretty sure my toaster will get a Roon update next year. What Roon does is to wrap music from your TIDAL or Qobuz subscription, Internet Radio, your computer, your smartphone, and your music server into a consistent user interface across a wide range of interface devices including your computer, tablet or smartphone. And it automatically picks up (through the internet) all the required metadata on each recording so you can see the cover, the liner notes, the recording date, artist and composer names, and so on. It makes the job of cataloging and organizing your collection so much easier. The attraction of Roon is not in its particular capabilities, though they are awesome, or how well they are presented. It's Roon's success in the market that makes Roon so attractive to us.
About exaSound's Delta Server
exaSound is conveniently based a few miles up the road from my apartment, and I have run into George at various shows and presentations. The last time was at the grand opening of the beautiful recording studio and listening rooms set up by Eli and Ofra Gershman. George was demoing the new Delta Server and explaining clearly what it did and why. Somehow some audience members took this as the ideal opportunity to explain that music is analog, and why shouldn't George expend his energies on making analog components instead. George was very diplomatic. I'm not sure I would have been in his place. George set up exaSound in 2010 to manufacture high-end DACs, networked music players and servers.
The company's mission is to empower audiophiles to enjoy studio master files the way they were recorded – at their original format, sampling rate, resolution, and number of channels. The company has developed proprietary asynchronous USB protocol, ASIO drivers and FPGA firmware to achieve a 32 bit, low-jitter, bit-perfect signal path. They were first to market with an 8 channel DXD DAC and the first DSD256 DAC (four times the SACD standard). exaSound sells direct and offers a 30-day risk-free trial in the US and Canada. The products are designed and built in Canada. By now, regular readers will know how pleased I am when I find top-notch audio products made in Canada. I'm happy to add exaSound to that list, which includes Bryston, EMM Labs, Reference 3A, Totem, Magnum Dynalab, Muraudio, Gershman, Oracle and Verity among others.
The Delta Server is a bare-bones computer running a very restricted Linux based operating system, using the most powerful Intel desktop processor and motherboard available that doesn't need a fan to keep it cool on maximum load. The chip in question is the Intel i9-9900. For nerds like me this eight-core chip runs from 3.1GHz to 5GHz. The Server is roughly cube-shaped and is offered standard without keyboard or touch-screen monitor, which you don't need for it to perform optimally. You can add a 7" monitor for troubleshooting network connections, or just to see what's playing. Inside the box there is room for three hard drives – SSDs preferred. The system drive in the standard configuration is a 128GB SSD SATA drive, although up to 2TB can be specified. This is attached to a M.2 slot on the motherboard. A partition on this drive holds the operating system, exaSound, and Rune Core software, while the second (shareable) partition (about 57GB in the standard configuration) is available to hold your music files and associated metadata.
The test unit came with a 256GB system drive, allowing about 185GB for my music files. There are two available 2.5" SATA3 6Gb/s connectors for more data drives, which can be up to 7.68TB each today and likely much more in the future. There are four external USB 3.0 ports – and you can add an expansion card to increase that number. I used one to connect the digital output to my DAC and a second to hold a SanDisk 256gb Ultra Fit USB 3.1 flash drive. There's a 60-Watt power supply, and 8GB of internal RAM, expandable to 32 GB. The power supply is external and provides 19V / 6.32A. An HDMI output is provided for the optional external monitor. Network connectivity is through a Gigabit Ethernet connection, and as a new option, an internal Intel 802.11 AC based wireless connection which can be used to support a limited number of zones. Eight zones are supported through the wired connection. If you want to rip CD's you have two options. You can attach a CD drive to a USB port, or exaSound can provide an internal top-loaded optical disk drive.
The Delta Server can operate as a Roon Core Server or as a UPnP server. The Roon Core manages your music collection, streams to your audio devices, and stores the Roon database on the internal system SSD drive. Music files can be stored on internal SSD storage, USB drives, and NAS (Network Attached Storage). Roon Core manages content from TIDAL and Qobuz and streams music to Roon Ready, AirPlay, Sonos, USB, and many other audio devices. You control playback through the Roon Remote app on your platform(s) of choice.
The Delta Server works closely with exaSound DACs, providing asynchronous packet streaming over USB that places very little load on the server's CPU. When connected to an exaSound DAC, the Delta acts as a certified Roon Ready player. Also, with USB-connected exaSound and third-party DACs the Delta works as Signalyst NAA endpoint, UPnP/OpenHome, and Airplay player. It supports high res PCM formats including FLAC, AIFF, WAV, and DSD (DSF and DFF). Its ENclusiv Hi-Res Audio support includes PCM sampling up to 768kHz/32-bit and DSD512.
You can get the Delta Server in black or silver finish. Unusually, the connections are underneath rather than to the rear, and the box sits on a low frame. This means to attach a USB key you need to roll it over and the key can only be so long to avoid hitting the floor. The power switch is hidden from view under the box, and only a small light shining down indicates if the box is turned on. These are awkward ergonomics, but then again, you won't be touching this often, and to its credit, the unit is built like a tank. The case is one giant heatsink to allow it to run fanless and silent, so it needs to be built like a tank. And in my use, single-zone (eight supported) it runs cool to the touch. It may warm up when you run multiple zones – each zone controlled by a different Roon app.
For this review, I hooked up the Delta Server through the supplied USB cable to my EMM Labs DV2 DAC reviewed here. I don't have a wired Ethernet outlet in my listening room, and I did not have an internal or external wireless connection installed on the Delta Server. So, to connect to my MESH Wireless Network, I used a wired Ethernet connection to a Linksys RE6700 AC1200 WIFI Range Extender which plugs into a power outlet in the listening room and offers a wired Ethernet connection in addition to its wireless output. Once connected, I turned off the wireless output which was no longer needed. I never experienced any problems with the connection. It proved rock solid. I was thinking of adding a hard-wired Ethernet port to my listening room, but this inexpensive option worked so well I forgot about it.
You will use two interfaces with the Delta Server. The first, which you rarely touch, is a web connection to the Delta Server itself, used to setup and for various administrative, troubleshooting, and support options. Basically, set and forget, and you can expect exaSound support to help you through these processes. There are links there to Roon Help and to exaSound Tutorials and the Owner's Manual. You can see how much space you have left on your data drives (internal and external), make those drives shareable across your network, and view a performance monitor which shows you the processing load for each core, and the temperature of each core and its allowable values.
You complete the initial setup, including connecting to the various streaming sources (TIDAL, Qobuz) or music files (iPhone, iPad, Computer etc.), and the various outputs devices on the Roon app. Then you can use the Roon app on any device to play music on up to 8 zones in your home. It's best to use a tablet or a PC for this as one major feature is not supported on the phone version of the app. You can't use or set a Focus on the phone app. A Roon Focus limits your music searches to specific genres or performers or specific file resolutions and so on – anything the metadata provides. So, if I only want to listen to Mozart and Cannonball Adderley on DSD, I can set that combination up as a Focus and apply it whenever I like. Come on Roon, add this handy option to the iOS app.
I won't review Roon for you here, but I will say it's easy to navigate and more intuitive than JRiver Media Centre which has been my interface in the past, and more flexible and powerful than the familiar iTunes. I will just mention a couple of features I like. First is the ability to search across all the music sources on the network, on TIDAL, on Qobuz and on the Delta Server itself, and see every version of a particular recording. Second is the ability to see, when a track is playing, exactly what the source is, the type of file and its resolution, and how it is routed to my DAC, including any bit rate conversion or MQA processing going on. If the selected source material is at too high a resolution for your DAC, the Delta Server will translate it to the highest resolution your DAC will support. Cool.
What I will tell you is whether the package works as advertised, and what kind of sound quality am I getting. Well at first there was a glitch. Twice in the first couple of weeks, the server became unresponsive and needed a reboot. Using the Delta internet interface, I was able to upload the logs to exaSound and they were was quickly able to spot the problem – a line of C++ code containing the name of my DAC did not have the expected text terminator. A fix was made available to me and to all users in a couple of days.
As to the sound quality, I have no criticism whatsoever. My EMM Labs DV2 locked on instantly to the USB data stream, up to the maximum resolution it currently supports on DSD and PCM material, and it displays that on its front panel, down to the MQA designation on suitable TIDAL Master material. I compared the sound quality from the Delta Server from all of its sources with identical CDs or SACD's in my collection, routed from the XDS1 over EMM's proprietary glass connection. Damned if I could tell the difference. And often Qobuz would offer me a higher resolution than my physical CD and I could appreciate the improved resolution. I will not get into a full review of MQA on TIDAL because that's a whole new subject on its own. But I will give you some highlights on extremely well-recorded albums that my extended experience tells me are repeatable across all music tracks.
For your entertainment, I'm including screen captures from my iPhone, showing the data path at each resolution and a picture of the front panel of my DAC, showing how it locks on to the signal.
This is what exaSound has set out to do – to provide a bit-perfect transfer of the data from wherever the source is, through careful control of low latency hardware and software. My DAC uses an asynchronous and galvanically isolated USB input to reject jitter and electrical noise, and I suspect those looking at an audiophile server will also possess a DAC with a sophisticated USB input. If not, you can use a network bridge to connect a wired Ethernet stream to your DAC's best input. Or you can upgrade your DAC now or in the future to take advantage of the high-quality digital stream the Delta Server can provide. You may also choose an exaSound DAC which offers even greater integration and flexibility. Like the reference EMM Labs DV2, exaSound DACs also feature galvanic isolation and asynchronous transfer.
Are there alternatives out there? Yes of course. Roon offers the Nucleus+ Server, which is a smaller lower powered box with far fewer expansion capabilities and no UPnP option, but still capable of bit-perfect transmission and high sound quality. And there are others, at a variety of price points. I can only comment on this one. The value proposition is high. It sounds great. I like it a lot. It's a keeper.