If you connect a DVI source to an HDMI display, you may have problems with the blacker-than-black. Technically, both are 8-bit formats, but put simply (because I don't have any better an explanation at hand) HDMI uses the color range from 0 to 255 while DVI uses 16 to 240 or so. As a result, blacker than black and whiter than white can get clipped off when feeding DVI into HDMI. In the case of the 990's switching, however, the DVI connectors are just pass-through - no video processing takes place. As a result, HDMI sources can go to HDMI displays without losing blacker than black and whiter than white.