Bose 901 Series ii

I own a set of Bose 901s with the equalizer.  I have them paired to a Carver pm700 200wpc amp, and am using a Harmon Kardon 630 for the pre-amp and tuner?  Any suggestions for something that might put out a little better sound and not break the bank?  And yes I know, no highs not lows must be Bose.