The HD-A1's analog audio section is at least as good as the 981HD's, but it doesn't support DVD-Audio or SACD - and for regular DVD viewing and CD listening you'll want to use the digital output from either player anyway, at which point the two will be basically indistinguishable since the analog work will be handed off to the 990.

There's definitely a lot of processing power packed into the 990, and the manual is good about presenting it in a pretty accessible manner. I offered some comments on your speaker setup issues here just a minute ago - the dialog problems you have been having could have been the result of having the center channel turned on even though there wasn't a center speaker present. You might want to set things up as I described in that other thread and re-visit those DVD's a bit to see if the dialog intelligibility improves.