I used to play bass through a trebble amp all the time because it was the only thing I had available. When I tried out some bass amps I got a much more satisfying sound. Sadly I wouldnt know what to recommend as it was a while ago and my 'affair' with the bass guitar didnt last long before I went back to being devoted to the trebble.

If you havent already, check out Geddy Lee.....he's a wicked bass player :) (get his stuff with Rush....the solo album aint so great)