A digital connection to the 990 bypasses the Denon's DAC. This isn't a bad deal, as the 990's DAC is excellent - I'd expect it to be better than the 1920's and at least on par with (or better than) the 2910's. For DVD-Video, I'd consider the DAC debate irrelevent - the vast majority of cases want digital audio from player to processor to allow the use of the processor's DSP and bass management. For CD's, the DAC issue is more relevent (many of us still listen to CD's in two channel), but I'd still lean toward digital connection - especially in the case of the 1920.

For DVD-Audio and SACD, we get into a different issue. To output these two formats, you must use the 5.1 analog output of the player. Both players support those two formats, so if you have (or plan to buy) any titles in those formats, you'll want to run connections from the multichannel analog output of the player to the 990's 7.1 Direct input.