three MORE suggestions for the OP...
Grayson,
1. One of the nice things about the Panny is that when you bi-amp it offers you the ability to regulate how much power goes to the tweeter vs. the woofers. If you are finding the Panny/Ascend combo to be overly "bright" you can thus send more juice to the woofers and less to the tweeters...since tweeters are generally much higher sensitivity, this makes a lot of sense and also can allow you to "tame" an overly bright tweeter.
2. In bi-amp mode the Panny also lets you do phase correction, i.e. compensate for the different depths of the tweeters vs. the woofers. Though to be honest I personally cannot really hear much difference doing this...of course I was not inputting very precise numbers just guesstimating.
3. Rather than use various EQ/sound-processing modes, I'd add to Shane's advice not to do that. Instead, I'd advise you to try something that I *only* advise owners of the xr55 to do: adjust the treble setting. Why? Because on the Panny, the treble control affects the topmost 20Hz frequencies rather than the typical 10-15Hz frequencies that most analog receivers use. So you can effectively reduce that topmost layer of brightness without unduly screwing up the rest of the sound.