Very good, Lee; not a bit surprising to me that you had no "break-in" period with your M60s. When I got my M22s I immediately fired up Mehta's performance of The Planets and was instantly thrilled by the sound. Now, about 8 1/2 years and maybe 25,000 hours of almost entirely classical listening later, still no break-in.
If for purposes of discussion it was assumed that the M80s were in fact audibly better, it seems to me that this would apply at all sound levels. Neither theory nor my personal experience(not with M60s/M80s)indicates that one of two fairly similar speakers using the same drivers would somehow have a more decided edge at lower volume levels.
Either of those receivers should supply enough volume, maybe just over 100dB on peaks, for fully-enjoyable listening.
Nice choices for music. My favorite Coppelia which I have is the Bonynge, which brings to mind the passing of Joan Sutherland a couple days ago. My favorite Shostakovich 5ths are the Jarvi and Previn. Listening to the KUSC stream at the moment.
