Power Amp Pairing

Aren't those components designed for each other? If you're still hearing something wrong and the preamp has been serviced, I'd get the amp checked out if you haven't. A general rule of thumb is to make sure the output volts of the pre is at least twice (preferably more than that) than the input sensitivity of the amp. If you have that you should be fine.

I can't suggest anything to pair it with to get the best synergy, but I can tell you from what I'm reading the amplifiers input impedance should be 10X that of the Preamplifiers output impedance. This is just a general rule of thumb, and my guess is this won't be much of a problem with most equipment. I have somewhat the same problem and have a nice preamp that was used in my headphone system, and I would like to get a power amp with it. I'm having the same issue of what to match it with since the manufacturer doesn't make power amps. I may purchase the amplifier from a company that has a generous return policy.