bryantm3, what model receiver do you have?
In the Multichannel setup of the player do you have the speakers set to LARGE? If they are set to small then your player may be cutting the bass to your mains, this could explain the difference between the analogue L/R and the multichannel because I think the bass management only applies to the multichannel outputs and not the analogue L/R outputs.
Your player has 2 sets of Bass management
1 is under 'SPEAKER SETUP' -> 'DVD'
2 is under 'SPEAKER SETUP' -> 'SUPER AUDIO CD'
So make sure you have both setup
cheers