Great post @krelldreams!
I’ve heard of some guys using the RM-10 strapped for mono, in pairs. I went to the RM-10 release event at Brooks Berdan’s shop in Monrovia, where Roger discussed the design of his little amp. After the talk I spoke with him for a while, and asked him if he recommended a pair of RM-10’s for use with stacked Quads (which I at that time had), or a single RM-9 instead. He said the RM-9, for its’ greater headroom..
The next time I saw him he told me he had been thinking about my question, and had actually changed his mind; he now would recommend a pair of RM-10’s over a single RM-9. I think I remember @clio09 saying the RM-10 had become Roger’s favorite push-pull amp of his own design. I use one with my Quad ESL’s (a single pair, not stacked). Being a Roger Modjeski fan boy (a badge of honour ;-), I have all three of his push-pull amps: an RM-9, -10, and -200, all Mk.2 versions.