Have you tried the direct digital connection to your display?
My set up is very similar to yours but I connect from the daughter-board on the M2A-VM HDMI (on-board graphics) directly to my plasma using HDMI-HDMI.
DVI-HDMI is a direct digital connection. Video-wise is the same as HDMI-HDMI, just no sound.
My connection to the TV was just a test (intending to build a specific HTPC for that). PC with TV card in is now connected by DVI-DVI (digital) to an 1920 * 1200 LCD monitor. PQ also very good, though possibly not quite as good as on the Bravia TV.