So I just got my mixamp pro and set everything up. I went into my audio settings and chose my SPDIF as the default out. Everything seems to work fine but I can't tell if I am getting the 7.1 virtual surround. Under the SPDIF settigns or the USB MIXAMP settings I only get the option to test out 2 channel audio.
Since the mixamp didn't come with any files to test it, what am I supposed to use to test the 7.1? How do I know its functioning properly?