Inexpensive, small form factor surround processor?

I'm looking for a small form-factor surround processor (something approx. the size of an 8-port ethernet switch or a cable modem) that will accept a SPDIF input and decode (at least) AC3/DTS, outputting 5.1 (or 7.1) line-level analog. Ideally, it would have a remote for master volume control. If it can decode Dolby TrueHD and DTS-HD Master Audio, that'd be even better though it would need an HDMI input to do so.

I suspect that something like this doesn't exist. If not, I'd appreciate creative input on cobbling something together.

One idea I had is a NUC PC running Linux with a 7.1 USB sound card. But what software do I use to decode the AC3/DTS?
 
Yeah, I have. Also Parts Express and just Google in general. All the compact units that I've found seem to "provide surround effect" - not decode AC3/DTS and they don't have a remote or any way to adjust the volume control. The units I've found that DO decode AC3/DTS and DO have a remote are full-sized components.