Can anyone recommend a professional, external sound card that will drive a 5.1 system (I'm looking at the BlueSky media desk) and allow for an Xbox 360 and PS3 to be plugged into it? (the 360 and PS3 have optical outs and HDMI).

Also, we use PC's here (so we can go USB or FIREWIRE) from the PC to the sound card.

It has to be professional enough to mix a game and, also, create sound assets in 5.1

HDMI is defined as being both audio and video, so in principle there cannot be any such thing as an audio-only interface that creates true HDMI.

I think that what you are looking for is a device that will create a HDMI stream from separate video and audio sources.

Here is such a device.

http://www.octavainc.com/HDMI%20switch%204port_toslink.htm



That would be a traditional USB audio interface with coax or toslink output.



Creating sound assets takes no audio interface at all, just multichannel audio mixing software of which many alternatives exist.

Are you saying you want to create a Dolby Digital multichannel digital audio stream? That takes other software. Please clarify