Which preamp for Quicksilver mono amps?

I use the QS 12at7 line stage with my QS amps. I find that it has way too much gain ( 18db )for a line stage. It is a very basic preamp and does not have a balance, mono switch and remote. If these features are not important to you I doubt that you would go wrong!!

If you want your QS monos to sing, it's really worth trying some different preamps with them. While I've helped a few friends with the standard QS line stage, and its a value for the $, do try a few nice lower gain (or switchable) 6SN7 preamps at least, you might be pleasantly surprised. I enjoy an upgraded Cary SLP-98 with my own QS Mono amps. Same as what @hilde45 mentioned above, give it a try for sure. 

I loved the Aesthetix Calypso with my balanced V4’s. 

What preamp are you using now and what specific improvements are you looking for.  Also, what’s your budget and are you looking for new or used?

I was using a Zesto Leto with the Mid Monos. That caliber of preamp really demonstrated how good those amps can sound.     

I used them with a CJ Classic 2SE and that was a really good sounding combo. Also used them with a Sonic Frontiers SFL 1 , sounded great.    

These amps are way under rated in my opinion 

I used them with other gear short term , McCormack RLD 1 wasn't a good match, sold that for the CJ