As tested by Stereophile your 350M's can give.
"maximum power delivery of a monstrous 475W into 8 ohms (26.8dBW), way above the specified power. 850W was available into 4 ohms (26.3dBW) and while I measured 1060W into 2 ohms (24.2 dBW)"
I cant see any improvement happening by going to the same topology even more powerfull 650M's driving your 90db speakers, as both amps would drive the 801n speakers on their ear.
This is why I ask what are you trying to get that needs to be different, and what is your source and preamp?
Cheers George