Thank you so much @Alstewart... You summerized my own M925 experience to a T!
The reason why M925 monos never get really hot to the touch is that they have an efficiency of approximately 93%.
Ther power is approximately 430W into 4 Ohms, reaching 850W into 4 Ohms. Their 2500W DC power supplies let them generate a peak current of 45A per chassis. I never heard them breaking a swet on my Vienna Die Muzik speaker, even with the extremely high dynamics of Mahler symphonies at high SPL.
The M925 have achieved recently a new quantum plateau in my system. I have adopted a full loom of Cardas cables in my system.... I started with the new flagship Clear Beyond XL power cords, and so to leave still room for future upgrades, the Clear entry level Reflection for XLR and speaker wires.... The result still stuns me: there is definitely a magic synergy between Rowland and Cardas, because I have never heard my system as refined and immersive as it is now.
Interestingly, the break-in process for Cardas wires appears to be quite benign.... About 300 hours likely takes the entire loom to over 90% of their performance potential.... Even from the first few hours one can tell that there is something truly special goiong on..... Of course, there is a bit of performance fluctuation for the first 70 or so hours, after which the performance arrow points steadily up. Did I mention that bass is spectacular and harmonic development is to die for? And I have heard sweetness of treble that I do not believe that any other wires have yielded until now.
Yes, I have loved my M925 monos since 2013 and have never suffered of an audiophilic wandering eye about them... But with the addition of the Cardas loom, these amps have achieved peaks of musical beauty that even I did not believe possible.
I am working on a detailed review of the Cardas loom in the context of my system.... I am still gathering some technical information.... I'll post the full review to Audiogon as soon as it is ready.
Saluti, Guido