Presently considering Herron M1's, Belles MB200's, McCormack DNA750's, Sanders ESL monos, Parasound JC1, some Krells, Classe's, and Parasounds stereo amps running in mono mode.
The Herrons could be on the light side at 275/4, not sure of the Belles model although Dave says this amp has much better components than the 350A's, the Sanders at 1600 watts would work but are very expensive, the JC1's are okay I guess, always wanted to try a Krell but don't trust them.
I Passed on a local sale of a Plinius 301 because I want monos even though that is a great amp.