Originally Posted by RickenBoogie
My first though was set up issue with the bass. The problem you put forth could be a "room issue", but that would not stand true for recording if you're going direct.
^ I'm kinda agreeing with this one.
I have a BX1500 as well and I'm not experiencing this. Lately I've been working on putting my studio together so I'm paying more and more attention to room acoustics than I used to and yes I'm noticing the differences of amp placement in my "jam room".
Some bass traps in the corners of the room may help out a bit.