They've come a fair ways since the 350. Maybe I can find one to review. Those AES outputs are begging to hookup to the Yggy.

  Do it!

Coax/SPDIF out from my mobos have been pretty horrible.

Using rca jacks from back panel or directly from the pin headers? Most mobos have very poor ttl to spdif converters with an electrolytic capacitor coupled output in most cases.

SD card readers are pretty unusual, but there are a fair number of network renderers that can accept USB thumb drives as local storage as an alternative to remote storage via Ethernet.

Some DACs can do this also. The Naim DAC for example has two USB inputs, which aren't for streaming via PC. They are used for playing music directly from a thumb drive.

Network renderer? I guess this is a device that purely plays media that's stored elsewhere on a conventional computer network. Would I be correct in thinking that they're more like a music dedicated pc, rather than a single purpose music player?

DACs that can play directly from usb, sounds interesting. Surely this means that the usb thumb drive input is like a dedicated drive; a transport.
Of course, it means that you're stuck with the sound/tech of that particular dac.

Has anyone tried such a dac, and A/B'd the usb thumb drive vs other inputs?

Network renderer? I guess this is a device that purely plays media that's stored elsewhere on a conventional computer network. Would I be correct in thinking that they're more like a music dedicated pc, rather than a single purpose music player?

DACs that can play directly from usb, sounds interesting. Surely this means that the usb thumb drive input is like a dedicated drive; a transport.
Of course, it means that you're stuck with the sound/tech of that particular dac.

Has anyone tried such a dac, and A/B'd the usb thumb drive vs other inputs?

In its simplest form, a network renderer has an Ethernet input, and a S/Pdif output for connecting to a DAC. It has no local storage, and normally pulls audio over the network from a remote storage device such as a NAS. It doesn't run its own media server like a music server (VortexBox etc) it instead relies on either the NAS, or another computer on the network, to do that job, for example Synology DSM, Minimserver, LMS, etc can be run remotely and handle that aspect.

Playback software is run on either a networked PC or a mobile device. Auralic's Aries renderer takes this concept further. It's kind of a quasi computer, running embedded Linux. Still no local storage, but it can play audio from a directly connected USB thumb drive, in addition to music streamed over Ethernet from a NAS. It has S/Pdif and AES outputs, and it can also act as a USB host controller, which most network renderers cannot. That means you can connect it to a USB DAC (if the DAC is compatible, not all of them are), if you want to use that instead of S/Pdif or AES. It doesn't have any kind of internal DAC.

Their new Aries Mini on the other hand keeps all of that functionality, while adding an internal DAC based on the ESS9018K2M, so it's one of the DACs that can play audio direct from a USB thumb drive, as well as stream audio via Ethernet. No USB required if you don't want it.

Naim's ND5 XS Renderer/DAC is the same. The front panel USB input is for local playback via thumb drive, and it can also stream via WiFi or Ethernet or conventional digital sources can be connected to its digital inputs, like a regular DAC, and output digitally via S/Pdif, or analog via its internal DAC section. The Naim DAC loses the network streaming capability.

I get the impression that the SDTRANS384 would be something of interest to look at. Seems to be built in a pretty totl manner.

Indeed : http://www.tachyon.co.jp/~sichoya/SDTrans/SDTrans4.html

I should hit them next time I go to Tokyo. Doesn't do AES though.