This is a tough one, not like demasoni's thread where everyone is piling onto the "get a sub" side of the argument (he has M22s). My first thought would be "leave it alone and enjoy"
I would think a better amp with more headroom would give you a slight improvement in sound quality, but I haven't found a lot of places where a sub really helps the M60s in a pure music environment.
I guess if the terms "pipe organ" or "Taurus" show up regularly in your album credits then a sub would make a noticeable difference -- eg. it does make a difference on the initial bass notes of "Dance on a Volcano" but doesn't make diddley-squat difference on "Meddle". Dark Side of the Moon CD didn't show up until after I had moved the M60s upstairs (away from the sub) so I can't comment on DSOM. I will be bringing the M60s down if anyone comes over to audition them so will play with DSOM on M60 with sub vs. without sub at that time.
I imagine the new amp would make a less visible difference but it would be visible on most of the music you play.
I didn't find that the sub made such a big difference on the electronic sweeps & runs in more modern music, eg. "Who let the dogs out" has a three-note low bass run during the chorus which the M60s handle just fine. "Burning Up" (Kylie Minogue) has a bass sweep which seems to go right down to DC -- adding a sub makes it "last a second longer" before the speaker stops trying but I can't really say it sounds that much "better" as a result.
This is probably no help at all. Can someone else jump in ?
