I agree with Hawkson here. The M60s will adequately cover your basses -- um, bases -- with the music genres you mentioned. Unless you listen to a lot of organ music, or deep bassy rock, the M60s are your best bet.

The sound will only get better, though, if you add a sub. One reason for this is that a sub takes over reprocuding the lowest octaves of music. This relieves the speaker and the amp of that duty, leaving more power and accuracy for the rest of the sound spectrum.