I still enjoy visiting your system page. You and I have a similar approach.
I love my MC240 and find it to be extremely transparent - but I have completely rebuilt it and thrown out all those worn out 50 year old caps and rectifiers. That amp on my Avantgarde speakers is the cleanest and clearest amp I've ever heard, whether tube or solid-state.
I fully agree with you that very-high-efficiency speakers are the only way to go. You just never get enough dynamic range and headroom with a low-efficiency speaker, no matter how powerful the amps driving them are. I'll never be able to have anything but horns now that I've got a pair in my music room.
Arthur