I've got the M9, sound is amazing, even better with Dirac implemented. The M5, MC-10 and AV860, as noted previously, are all essentially interchangeable as they are built on the same platform. The M9 adds better DAC's and a few other features. I moved from a Marantz AV7703 and Yamaha CX-A5200 to the Maestro M9, the M9 sounds far better IMHO, even without Dirac engaged. Musicality is especially good!