Do you prefer the M2.2 over the M1.2 , or only if in the case where the speakers are a tough load ?
I actually prefer the M2.2 yes. It's got IMO more flexibility/versatility. While the 1.2 has more "feel" to it in the midrange probably because it is true Class A vs A/AB the 2.2 has more control and a bit more headroom. I like my kicks and my bass lines rock solid and visceral, my tympanis rolling and roaring. If you were to ask me how much of my listening is to small ensembles and easy listening I would say it would be at 25 to 30% only. I found that I could get close in the feel department to a stock tubed 1.2R by using tubes like the Mullard CV2492, Valvos and Amperex Blues. The 1.2 is only a few hundred bucks more expensive, with NOS tubes the 2.2 gets right in there price wise. Top 6922/6dj8s don't cost nearly as much as say top NOS 12ax7s. An instance where I would handily choose the 1.2 Reference is if the system were in a small room. It really does have the edge in harmonic texture and nuance and in a smaller room it wouldn't need to be asked to do nearly as much in the midbass as a large one.