Help! I'm trying to get 5.1 channel out of a PC digitally into the DAC in my AV receiver. I've tried 2 different USB to SPDIF devices, PC Link (http://www.cryo-parts.com/pclink.html) and Cables To Go 22327 USB 5.1 Audio Adapter. All I get is 2 channel. (2 channel works fine). Both use Generic USB Audio driver.

Machine is a PC running Vista with Realtek onboard audio. The chip supports 5.1 & SPDIF, but Acer did not put an SPDIF jack on the machine.

Source data: I've tried downloaded 5.1 files. I've played DVD's. Media Player Classic software says it's outputting 5.1. Control Panel Playback devices shows 2 channel output through "SPDIF Interface" (it's connecting to the AVR, but not in 5.1)

WinDVD dims out SPDIF Passthrough, allows analog only.

Interestingly, when I disable the Windows Audio Service, all the devices in control panel sound that would only offer 2 channel are now offering 6 or 8. WinDVD is offering SPDIF passthrough and surround sound. Only problem: no sound comes out.

Re-enable the Service, sound comes out but 2 channel only.

any thoughts?