I have been messing with that setting for awhile now and can't get it to work. Do I need to come out of the PVR-350 and go in to my sound card?
Does your card come with an audio out connection that you must plug a wire to connect to your sound card?
I am guessing the answer is Yes. If so, you need to make sure that on MC TV's configuration, Audio page, you check the check box "There is a physical audio connection from my TV tuner card to my sound card", and select the right mixer device and the right sound channel (which ever channel your connection is made on the sound card, usually Line-In).
A second area to poke around, if the above does not work, is to go to "Advanced Properties" tab, and double click "Video Crossbar..." (or "Second Crossbar ..." if it exists). In the resulting dialog window, choose "Audio Decoder Out" from Output drop-down box, and then make sure that in the Input drop-down box "Audio Tuner In" is selected.