Which preamp for Quicksilver mono amps?

Check out. Linear Tube Audio, it’s $5-6k  and takes several tube choices 

it is designed by David Berning, then further  improved upon ,Made In USA 

and sounds great.

I'm using a Herron VTSP-360 with my V-4s

I too have heard them with an Aric Audio pre and the match was amazing!

Call him, his customer service is as legendary as his tube gear.

I am not looking for any sound improvement. I have not yet thought much about matching KT mono with QS preamp, but since QS preamp is relatively cheap ($1500)

I wouldn’t bother.  Just put the $1500 towards a real future upgrade like the Spatial Raven, Aric Motherload, etc. that are on another level entirely.

+1 on CJ recommendation.