Amplification for Denon 3802 for 2-ch listening

I'm just getting started in the home theatre / mid-fi arena, so please bear with my ignorance... that's why I'm researching here.

Current Setup:
I recently purchased a Denon AVR-3802 for home theatre use, based on a friend's recommendation. I got a good deal on it, and I like the processing features for HT. That purchase has started a snowball effect. I then decided to upgrade my speakers, and I took a quantum leap up to B&W CDM 7NT's for the fronts, the CDM CNT Center, and a used set of CDM 1SE's for the rear surrounds. I also have a REL Q150E sub coming next week (I know it's a little small for the 7NT's, but space was an issue with my wife, and it seemed pretty powerful when I auditioned it at a local shop). My source components aren't that great, and I will be upgrading those along the way. I have a cheap DVD player, and an older Sony ES CD player. I did buy decent quality interconnects and Canare star-quad bi-wire speaker cables for the whole system.

Question:
I'm relatively satisfied with the sound of the system for home theatre (although it does seem like I have to crank up the volume to about -15db on the receiver to get the full effect), but I don't think I'm doing my speakers justice for music listening with the Denon powering them. I'd guess my usage of the system is about 65% music, 35% movies. I'm looking for recommendations on an amp or amp / pre amp combo to improve the performance of my speakers for music (and home theatre, if possible). Does it make sense to use the denon as a preamp for music, or should I take it completely out of the loop and only use it for HT. If the latter, how do I do this, and what features in the preamp should I look for? I have a budget of $1200 for this (I'll buy used gear).

Thanks, and sorry for the long winded question.

Scott