Sorry if I'm being repetitive here, but the Adcom GFA-750 is widely considered to be an outstanding stereo preamp and it offers an HT pass-through. Very dynamic and transparent. Unless you're looking for tubes I think this one will be tough to beat, and you can get one new for a street price of around $1200(used for around $750 although I wouldn't recommend it) and not have to worry about buying a used preamp. Plus you can probably demo it in your system to see if it works for you before you buy it.
Also in the solid state realm is the McCormack RLD-1 which also has the pass-through feature and is a little more tube-like than the GFA-750. Levinson/Proceed offers a pass-through but I don't know if you could hit your price target even with a used unit. Without the pass-through I'd consider something used from Pass Labs or maybe the Musical Fidelity A3CR.
On the tube side you can find stereo preamps with pass-throughs from Sonic Frontiers, Rogue, BAT, Audio Research, Conrad-Johnson, PSE, VAC, and probably a few others. My top recommendation would be the Adcom for performance, value, and ease of use in an HT application. Hope this helps and best of luck.
Tim(the other Tim)