Wilson Sophia 3 speaker and preamp mcintosh C50 .... Which power amp is suitable!!!!

I agree, they will work with them, that why I said it may sag a little. If then you use an amp that could deliver far more current into this load, then thing could change for the better again, to even give better bottomless pit of bass info and outright power.

Cheers George   

http://www.stereophile.com/content/wilson-audio-sophia-series-3-loudspeaker-measurements#Bg6XMa0CYPECFV8F.97

Look at the tests done on these Sophia’s, the last 2 sentences first paragraph, indicates that many amps that have output transformers (tubes and the MC452) or amps with limited current ability, will sag a little current wise in the bass, and because of that will give a brighter presentation to the balance of the speaker.

Look for amps that have good current drive down to 2ohms if you want a more even natural balance, as Wilson would have voiced them. Probably with Krell or D'Agostiono amps or such.  

Cheers George