Your Bat VK pre's are good. For cheep, with the right tubes, Audio Research's are workable as well (usually a slight bit bass bump I've found). Passives are transparant enough, yet lack dynamics a bit(not a problem from a "pass through" standpoint for an HT pre/pro). In that case, used Pass Aleph L, McCormack TLC, similar.
IF you can find a used Cary 50(retailed for $1200) w/o remote, that is stellar sounding as well!
I think you might not go wrong with the BAT as suggested above however.