Looking for pre with 2 volume controls.

"I have 2 different mono amps..."
Perhaps you should consider getting matching amplification for each channel instead?

Lamm preamps use dual volume controls if you're looking for a tubed linestage.

Maybe I'm a little slow. I understand having two different stereo amps if you are powering say the upper panels of speakers (such as martin logan speakers) and the woofers are powered by a different stereo amp. If the power levels of the amps are "matched" and an electronic crossover is used to "balance" the high and low signals.

That way, one did not need the same amps.

But if one amp will power one speaker entirely and the other "different" amp will power the other speaker, I can't see how they will ultimately sound different. Right and left will be different.

I would love to hear the logic from a dealer/sales person that recommended two different mono amps.

I really think I'm missing something here.

But if I'm not, if your existing pre-amp is a good one, I would keep it and get a matching amp (if you like the sound) instead.

in any case, enjoy

"I would love to hear the logic from a dealer/sales person that recommended two different mono amps.

I really think I'm missing something here."

Maybe the OP is trying to integrate a center channel into an existing system.

I've used Croft Acoustics preamps since 1987 with the two volume knobs. I guess the logic is a cleaner signal path by giving up the balance pot.
I have no problem using them.