Lower .1 output on the 5.1 analog outs is a common problem. In a few articles I've read, it's not clear if the problem is in the receiver end or the dvd player end. The solution is to calibrate with Avia (or other disc) and bump up the .1 output either at the player or at your receiver. My receiver has a separate set of channel level settings for the 5.1 analog inputs.
Also, if you read the very long thread on the 563A, there is a link to a review that one of the members did which goes into a good bit of detail on the bass management behavior of this player.
btw, has anyone else noticed that the price of this unit has plummeted recently. The local Best Buy has it for $135.