Look at the NHT SW2Pi. It is a pretty quick sub that works well with music (not too boomy) If I can remember right, I bought mine for around $700-800. Used probably pretty cheap. It comes with its own EXTERNAL 120W power amp.
Help with Subwoofers
I am looking for a subwoofer to mate with my Monitor Audio 5i's. I have a modest budget (reason for the 5i's @650/pr). My preference is for musical and accurate sound versus earth shattering, chest rupturing bass. The MA ASW210 is supposed to be a good unit with dual 10" drivers ($795 used), but can anyone suggest a better (or comperable) subwoofer for lesser $$. Thanks