I've recently had an interesting experience. We've just finished alterations on our house and one of the outcomes is that my daughter's piano moved into our TV room. At first I wasn't thrilled about this but once we (OK, a whole bunch of us, the thing is jolly heavy) got it in I tried out my AV system and I'm sure the sound has improved. The room used to have serious problems with booming bass but these have largely dissapeared. I went round the piano tapping it with my knuckles and have noticed that it has a series of thin wood pannels on the front which I presume are meant to resonate when you play it. Could these be absorbing some of the errant bass frequencies? I read somewhere that the lowest note on a piano is 27hz and so it makes sense that it should handle low frequencies well.