PS Audio M700s or older Bryston 4bsst / 4bsst2 ?

How exactly do you know when they'll need to be recapped?  

When they start leaking and/or the SQ squares off. Distortion.

There must be someone you can borrow an amp from. I recently compared the Belles MB200 monoblocks to the PS M700 monoblocks and found the M700' to be superior in everything but giving off heat. I liked the Belles, but the PS had more dynamics and details.

((((Can I remove the power tubes from my SLI 80 and use the “subwoofer out” jacks to send the signal to my amp. That way I could have a remote-controlled preamp. koestner)))
Koestner,The Pre amp is way more important in driving amps I would suggest you get a real preamp with decent matching Gain ARC, Belles ETC. The Belles amps you listened to will wake up and should then easily convince you of their abilities and superb performance. Best JohnnyR

It's unusual that you would find a different post of mine and stick it into this one. I never used the SLI80 as a preamp. It was just a curious question if it would work with no power tubes. I compared the Belles to the PSA with a real preamp (Belles VT-01) and it was just as I said. The PS audio amps had more dynamics and detail.