Speaker-amplifier "matching" is a myth, IMO. You will get equally good results with either amps. However, the M2 and M3 have quite different sonic characters -- the M2 is more crisp, forward and detailed (like the M22/M60/M80), while M3 is more mellow, relaxed and laid-back (like the M40/M50) with a bit more subjectively pronounced bass. It is up to your preference (many people here seem to consider the M2 more "accurate" to the source, though).
I also suggest you look at pre-owned stereo amps from reputable brands at AudiogoN.com and other similar sites. Stereo amps have not significantly changed for many years. You will save a lot by going with used gears.
