I’ve used Aurender’s W20 music server as my reference since reviewing it in Issue 258. I chose the W20 for its combination of outstanding sound quality, features, and its superb music-management app. The W20 has been at the front of my system throughout many different changes in amplifiers, cables, loudspeakers, and even rooms, but during that time I’ve never had occasion to question its performance or wish for something “better.” That’s a remarkable statement in the rapidly advancing world of digital audio, particularly in music servers.
But the Korean company has been quietly working behind the scenes to make its flagship platform even better. The result is the new W20 Special Edition, a major overhaul of the original W20. The “Special Edition” moniker is a bit misleading—the W20SE isn’t a higher-end option over the standard W20. Rather, the W20 has been discontinued and replaced by the W20SE, with a price increase from $17,600 to $22,000.
Before looking at what’s new in the SE, let’s recap the original W20. Aurender’s top music server is a network-based system that stores music on its internal hard-disk drives and streams music from Tidal, Qobuz, and Spotify (in addition to Internet Radio). You simply connect the W20 to your network, run a digital cable from the W20’s output to your DAC, and manage playback (streaming or stored music library) via Aurender’s Conductor app on your tablet.
The original W20 is a full-size chassis containing a computer built from the ground up specifically for audio, two 6TB hard disk drives, 240GB of cache memory, and a digital-audio output clocking circuit. The cache memory buffers the signal so that the digital data are clocked out of solid-state cache memory rather than directly from the hard drive. In fact, the disks are turned off when the W20 is outputting a signal. I’ll refer you to my review in Issue 258 and at theabsolutesound.com for all the technical details, as well as a description of the excellent Conductor app.
Aurender has taken this superb foundation and upgraded many of the subsystems. First, the spinning hard-disk drives have been replaced by 4TB of solid-state memory. Although that’s a reduction in storage capacity from the W20’s whopping 12TB, I’ve found that 4TB is plenty of capacity, particularly as streaming occupies a greater percentage of my listening. The advantage of solid-state memory over spinning disks is greater reliability and less vibration. Because of the W20SE’s cache memory, which acts as a buffer between the disk drives and the output circuit, it’s unlikely that the switch to solid-state memory has any sonic benefit. Yet, I remember my experience with the PS Audio Digital Lens, circa 1996, a device that took in a digital stream (from a CD transport in those days) and buffered it through a FIFO (first-in, first-out) solid-state memory before outputting that data stream to your DAC of choice. Despite the Lens’ solid-state buffer, I could still hear differences between CD transports. Although it defies common sense, solid-state drives may sound better than spinning discs. In addition, my recent experience with the Fidata solid-state network storage device suggests that the storage technology affects the sound.
The W20’s 240GB of cache memory has been expanded to a whopping 1TB in the W20SE. The solid-state drives and cache memory are housed in a “vault” of machined aluminum within the chassis for quieter operation. The W20’s switching power supply has been replaced by a linear supply to reduce noise inside the chassis. (Switching supplies can radiate noise.) This supply powers the CPU board, not the audio processing circuits, which are powered by batteries (as they were in the W20). The output clock has been upgraded for lower jitter. As with the W20, the W20SE’s output signal is processed by a digital phase-locked loop implemented in a Field Programable Gate Array (FPGA), with the reference frequency generated by an oven-controlled crystal oscillator. The W20SE’s PLL and output clock deliver superior performance over the W20. Finally, the LAN ports now have “double isolation” to prevent noise from entering the W20SE.
In addition to these hardware upgrades, the W20SE also sports new features, including support for native DSD output up to DSD512. DSD-over-PCM (DoP) supports up to DSD128 (the W20 was limited to DSD64). The DoP format structures the DSD data so that it looks like PCM to the hardware it encounters. The datastream is converted back to DSD at the receiving end, with no loss of information. The core idea of DoP was invented by dCS in 2011 and developed into an open standard by a group of audio companies including Aesthetix, Merging Technologies, J. River, Vitus, MSB, and others.