I've got an Ampeg B15 and it has the original CTS speaker in it. I don't mind how it sounds but I've heard that the JBL D140f sounds better but finding one could be difficult. Obviously a Jensen, Celestion or Eminence is an easy option. Would getting say one of the high power handling (400/500W) Eminence speakers have any advantage over a lower powered one in what is a relatively low powered amp? Could anyone suggest a speaker that could get the best out of the B15?