Which preamp for Quicksilver mono amps?

Thanks for all your input.

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?

My preamp is Audible Illusions M3B. Amp is KT Mono with KT150. 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 am interested in trying to compare with AI. I just have about $1500 to spare, so if I go for other brands, it should be a used one.

@ihcho you could do a lot worse than your AI M3B with a lessor preamp.You have a decent unit now. Echoing @soix ’ fundamental questions about what you are trying to accomplish -or- just to satisfy curiosity itch - do share more. 

A friend had a preamp like yours, IIRC some of the later AI units were designed to be used with some of the higher gain Russian 6922s although people do try others. 

Have you already checked and tried really good 6DJ8 / 6922 dual triode tubes in your unit? What’s in there now?

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