I was wondering what sonically happens when you combine a preamp and power amp from 2 different manufactures? For instance, I have a Rotel preamp, and naturally was going to buy the matching power amp, but found a good deal on a NAD power amp. Which will be the predominant component-in other words...will my system have the NAD sound or sound like the Rotel? I always thought that the Power amp section is what gives the sonic character, and the preamp is just really a source selector, and volumn control. Would it just be better to match the pre/Pwr amps from the same company?

it was done for years in the 60's and 70's what ever fit your needs and budget for a pre amp
and generally two mono blocks of considerable quality.

Is there any chance you can audition both and decide for yourself?

No. That is why I was asking here, to be informed before I make a purchase.

I think it should be okay to mix and match but be aware of the 2-prong vs 3-prong plugs. They have very different signal grounds that can potentially cause hum and noise and cancel out the advantage of balanced connections.

Its more than okay to mix and match brands. I do it. Both the preamp and amp will impact and affect sonic characteristics.

use what you like...

The Rotel and NAD are VERY comparable. I've listened to both and can hear very little if any difference

Mixing and matching is one of the best reasons to go separates. You can choose what you think is best/right for the job.

part of the idea of going with separates is that it gives you the ability to mix and match. Perhaps you need a lot of power, but like tube sound, you could mix a tube preamp with a solid-state power amp.