Good preamp for under $300

Check out the B and K Pro 10 MC. This is a great piece for your price range, has an outboard power supply and a phono section. Great american build quality.. no tone controls and a bypass mode.
Best of luck,
Joe
Custom Audio LLC

check out the McCormack Micro-Line Drive. It has passive and active outputs and an outboard transformer. It is a very good bargain at $250. It is a gem. Salsero

Adcom GFP-565 is a nice piece in your price range

Audioman, what's a bypass mode?

Kkat,
Bypass mode is using the preamp purely as a pass thru for your source to your amp... just using the volume pot. not the gain section of your preamp. You dont get the same volume levels as when the preamp is active. It is supposed to be a more sonically pure way to listen.. I personally like the sonics of the pro 10 without using the bypass mode imo. The external power supply is rock solid and it is a good thought on B and Ks part to isolate it from the rest of the electronics.
It is just one of those nice pieces...
Best of luck,
Joe