If you have to much gain (very little volume control) you can also replace V2 with a jumper plug to lower the amps gain. I run Avantgarde Duo Omegas with M60s with only 4 tubes per amp and V2 jumper-ed out. Atma-Sphere can set you up with a pair of plugs or you can DIY them if needed.
Zu speakers with Atma-Sphere M60 amplifiers
I own the latest version of the Atma-Sphere M60 amplifiers. Arriving soon are a pair of Zu Definition speakers. Does anyone here have any experience driving the Definitions with the Atma-Sphere M60 amps. Observations are most welcome. I am given to understand the Definitions are approximately 6 ohms. I'm hopeful this will still work satisfactorily.