I agree with Gonk on using the analog outputs as opposed to using optical/digital outs. IMO, the DACs in the BDP-83 do a much better job than the 990. Also, if you are listening to 2-channel material then I recommend the stereo analog outputs on the BDP-83 as those DACs are higher quality then the multi-channel ones. I did quite a bit of A/B testing and even did some blind testing and I always found the analog outputs, especially the stereo ones, to sound much better. Admittedly having a large number (in my case 7; 5.1 and stereo) of analog cables running between the BDP-83 and the 990 can be cumbersome, but I think it is well worth it.

I do not use any of the digital signals for audio from my BDP-83. When I am watching BD-DVD I like to use the latest audio formats, which the 990 can't decode so again I am back to using the analog.

BTW, when you are looking for analog cables you don't need to spend a ton of money on them. I have the Outlaw PCA cables and they do a great job for a relatively inexpensive cable. My only complaint with those cables is they are the kind that has a locking collar that you twist to make a tight connection. This was a great idea, however they are very difficult to use on the 5.1/7.1 connections since the connectors are so close together and the cable ends are somewhat larger than normal. If I had to do it over again I would probably go with another brand that had smaller connectors.