Looking for a USB sound card with optical out
I've done some cursory Googling and such, and not come up with anything concrete.
I have an Acer Revo (single-core Atom 1.6GHz, 2GB RAM) as an HTPC running Ubuntu 11.10 and XBMC. Everything works fine, apart from one detail - the HDMI audio adapter works and passes the audio to the TV, but even though my TV is hooked up to a high-spec amplifier with optical SPDIF, it only passes through stereo from the Revo to the amp. I would really like to have 5.1 surround sound from the Revo, but there seems to be no way to connect it up as it is.
I've used optical SPDIF in the past and have blown away by the quality. So, I'd like to add a USB sound card with optical out, and hook it straight into the amplifier. In theory, if I tell XBMC to use the USB sound, it should pass the audio straight to the amplifier to decode, right?
My question comes as, can anyone recommend a card that works like this under Linux? I've had a look at some Creative USB devices, which aren't very expensive, but I really need one where optical output is known to work. Hopefully latency won't be a problem, since the Atom isn't being stressed too badly with XBMC - the ION graphics chip handles a lot of it, and it's running as its own session, not on top of Gnome, to save RAM.
Any suggestions? I'm looking to spend not more than £50 on this.