Suggestions for my system: Preamp?

Especially for a recent college graduate, I am lucky to have such a nice stereo. It includes:

Magnepan 1.6QRs
NHT 12" powered subwoofer with an external crossover
Arcam CD-72T
Bryston 4B

Currently, my father's old Yamaha prologic (bah!) receiver is serving as my preamp. Also, I have AudioQuest cable, some decent interconnects (50 to 100 bucks a pop, not toooo expensive but not toooo cheap), and a Monster HTS1000 power conditioner.

I've been told that I really need a replacement for the Yamaha preamp. However, the entire aforementioned system was purchased for only 2 thousand dollars. Because I really don't have much cash, I've had to find excellent bargains and values.

So if you could kindly drop some suggestions for preamps that cost less than 750 used, I would appreciate it! My two criteria are: 1) It must be of sonic equivalence to my other components and 2) Must be able to send my towers AND my subwoofer a signal without using a Y splitter (i.e. the preamplifier must have more than 1 set of outputs). I really don't know where to begin looking, so thank you for your help!