Best Pre-Amp w/Throughput for HT ?

Depending on how much you want to spend and if you want a tubed pre or solid state pre, I would consider at least listening to the SOnic Frontiers Line series or the Adcom GFP 750. They both have a HT bypass loop and work very well in 2-channel mode as well. I tried the whole calibration thing with a pre amp that didn't have the processor loop and I didn't like the fact that I couldn't control the volume of my theater in variations. Meaning, that if I wanted to hear the movie but at a lower volume inwhich I originally had it calibrated to, I would have to recalibrate my system just to turn it down to a lower level. I believe that Proceed and EAD makes some nice pre - pros that you might find used and at a fine price and possibly may give you the performance that you're looking for in a one box unit as well.

Good Luck.

With the gear that you have now, I would give strong consideration to either the Mark Levinson 380 or 380S, both have the home theater bypass... go with the "S" version if you can swing it.
Alternately the Krell KRC-3 also has an HT blow-through circuit.
My first choice would be for the 380S.

Might want to demo a Theta casablancaII while your out and about.

Some of the high end Conrad Johnson preamps have the throughput for HT built in. I am only familiar with the Solid State PFR which has it, but I believe their are others.