System information

layout the board for the best electrical performance separates the men from the boys. Powering this
motherboard is a high quality switch mode power supply. This supply only powers the motherboard, hard
drives, and front panel OLED display.
The W20 audio board is isolated from all other parts of the server by an infrastructure of thick aluminum walls
and plates. This board contains a single oven controlled crystal oscillator and high quality parts throughout.
Of note is the special USB audio port, dual wire AES/EBU ports, and word clock BNC input. The USBaudio port
was design to deliver the cleanest possible signal to a USB DAC. (The Aurender W20 has no onboard digital to
analog conversion.) Thus, the USB port's location on the audio board rather than the main motherboard.
The USB audio signal is buffered, using a proprietary buffering circuit to reduce noise and jitter, prior to
transmission to a USB Audio Class 1.0 or 2.0 DAC. The USB audio port's 5V / 1.0A power output can be
toggled off and on within the Aurender iPad application. This feature is very nice when connecting to
a USB DAC that doesn't require power from a computer such as the Ayre Acoustics QB-9 DSD. There's no
sense in sending an unneeded power signal even if it's clean as a whistle. The Aurender W20 runs a custom
version of Linux that supports many external USB DACs. There is no user interface to install special device
drivers for USB DACs that aren't supported by Aurender's Linux such as those from M2Tech (some not all
models) and Mytek. I've tested several USB DACs with the W20 such as the EMM Labs DAC2X, Benchmark
DAC2 D, and the Berkeley Audio Design Alpha USB. XMOS based DACs work great for the most part. As a
general rule, USB devices that work with Mac OS X without the need to install software / device drivers will
work with the Aurender W20. Users with DACs that support other audio interfaces such as AES/EBU,
coaxial S/PDIF (RCA & BNC), and optical S/PDIF (TosLink) needn't worry about compatibility with the W20.
These interfaces are standards that just work between all devices. More on the AES/EBU interfaces in a bit.
Powering this isolated, both electrically and physically, audio board are two banks of lithium iron phosphate
(LiFePO4) DC batteries. These banks alternate charging cycles to eliminate negative performance effects of
low batteries. No user intervention is required, the audio board is always powered by these batteries. The
audio board is also isolated from annoying ground noise emanating from the mains outlet powering the rest
of the server. An additional bank of LiFePO4 batteries is used as a UPS (uninterruptible power supply) when
power is removed from the server altogether. This temporary battery supplies the mother board, hard drives,
and OLED display enabling the server to shutdown gracefully and inform the user what's happening via front
panel display. The W20's batteries are spec'd to last 3,000 charge-recharge cycles until they reach 80% of
capacity. If the W20 is used eight hours per day, 365 days per year, the batteries should last about 40 years.
The Aurender W20 features two AES/EBU outputs so it can operate in single or dual mode AES. In the
simplest of terms single AES uses one cable and dual AESuses two cables. Both single and dual use digital
cables with XLR terminations on each end. This is one major differentiating factor between the W20 and
nearly all other music servers on the market. The reason for dual AES on the W20 is that some very high end
digital to analog converters from companies such as dCS, Esoteric, and Chord support or require dual AES for
sample rates over 96 kHz. The ultra rare and long out of production Pacific Microsonics Model II requires
dualAES as well. The Dual AES feature of the W20 is enabled or disabled within the Aurender iPad app. Set it
once and forget it.
Along a similar line as dual AES, the W20 supports word clock input. Many of the same DACs from dCS,
Esoteric, and Chord support word clock output. Systems from dCS and Esoteric are often configured with a
separate master clock component that feeds word clock to a physical disc transport, a DAC, and even an
upsampler. This same master clock can feed the Aurender W20 thus all the digital components are fed by a
single master clock. Clocking is a big deal in digital audio. The fact that the W20 supports word clock input is
another major differentiator between it and the competition.
During the review period I received a dCS Vivaldi system without the physical disc transport. This consisted of
the Vivaldi DAC ($34,999), Vivaldi Upsampler ($19,999), and Vivaldi Master Clock ($13,499). Combined with
the dCS stack the W20 fits like a glove. dCS and the Aurender team worked together to enable the W20 to
communicate with dCS components via RS232. My W20 shipped with a solid aluminum USB to RS232
converter for this communication. Once the dCS Master Clock is connected to the Upsampler, DAC, and
Aurender W20 via BNC word clock cables, and the W20 connected to the Master Clock via USB-RS232 the
entire system works beautifully without user intervention. Users of dCS will understand what I mean when I
say this is a complex system capable of delivering fantastic results. There are other methods of clocking
without this W20 - dCS RS232 communication, but the results aren't nearly as good as this preferred setup.