Quicksilver Mid Mono - power matching


Looking at a pair of QS Mid Mono tube amps. It looks like they put out 40-50 watts depending on the tubes. I'm trying to figure out how much speaker I can power with these. I've heard sensitivity is an important concern and that I should be looking at speakers with 91db or more? Is that good advice? Do folks have thoughts, guidance on this?
spotconlon
I have used them with Revel M106, plenty of power...PSB M2, a 4 Ohm speaker...drove them no sweat.  Current and favorite pairing?  Mid Monos with my Heresy III.  Great combo,  but the latter mentioned combos sounded excellent too.    

I am using KT 77 and they work well in the Mid Mono
@spotconlon 
Are you gonna snag those recent model mid monos listed on USAM? The newer ones with brass speaker terminals don’t show up that often, fwiw. People keep them for decades, usually.

Disregard. SOLD today.  Went fast. 
@decooney I bought them 😉 also picked up an Aphelion for the P6. Now for the pre, the speakers and the interconnects. 
@spotconlon
Nice, glad you got them, congrats!

The QS Linestage Pre is a bargain, fwiw. Add some nice vintage NOS tubes, done. Silver non-remote version is preferred by the sonic purists, remote version comes in Black only. If you use a RCA/out to a sub, you can send the Linestage to Mike at QS to convert TapeOuts to 2nd Pre/LineOuts. Ask @hilde45 here on Agon, he went this path with success.  

If there is any chance a local dealer will work with you to demo some speakers, it helps vs. online buy/try/ship back multiple pairs...