In reply to:

The rio doesn't have a digital output, so there is no way it can send 5.1 signals to a receiver.

Isn't someone adding digital audio output to the Receiver hardware? I think the approach is to replace the power speaker/amp daughter board with a board that provides SP/DIF out? The intent is to provide simple stereo (two channels only) output in the SP/DIF format.

If the Rio were able to do stereo SPDIF in a setup like this, I don't see any reason it couldn't do 5.1 as well. The difference between 5.1 over SP/DIF and 2.0/stereo over SP/DIF is simply the bit rate and encoding of different numbers of channels, right? If so, wouldn't the Rio be able to simply "pass through" the 5.1 stream, letting the downstream componentry do the decoding?

I don't see the Rio doing local decoding from digital to the six analog audio channels provided by 5.1: (a) there are not enough analog connectors present on the Rio client hardware, and (b) as Andy said in a previous post, there probly aren't enough horses under Rio's hood to decode six high bit-rate audio channels. DVD audio has like twice the bitrate of CD audio [per channel], doesn't it?

I'm not sure, however, that I see the point of using 5.1 with audio only (implying music only?) content served thru the Rio. I love 5.1 when watching DVD movies on my main A/V system. Movie sound effects are very directional and are placed much better in the sound field with five directional speakers, as compared with using a fewer number of discrete channels (e.g., Dobly Pro Logic provides only four channels; the rear surrounds share a single channel; also its channel separation is somewhat poorer). The pounding sub-woofer being driven by the ".1" channel is a huge addition for explosions and the like.

But when I listen to music on the main A/V system, I put it in plain old two-channel stereo mode (well, "2.1" including the still active sub). I leave all of the effects decoding stuff entirely disabled. Note that Dolby Pro could be applied to the two-channel material, but this often makes music sound weird.

So if the Rio client can only stream audio, how much sense does it make for it to provide 5.1 at the client's remote location?