Why don't you check out Yamaha's DSP-A1 Integrated amp? It's a few years old, has fantastic sound, and will do everything you need. Believe me, I have 2 of them, and they are ever bit the equal of my McIntosh separates. I've tried the route you want to go, and it is a pain! You can pick up mint DSP-A1's for around $650-700. Original cost when new was $2700 in black, $2850 in gold with rosewood side panels, so they are quite a bargain now.
How to add to my 2-chanl int. amp for home theater
I have a good two-channel integrated amp I use for music. I'd like to move to home theater inexpensively, that is without replacing my entire system. How can I add to what I have to get surround sound processing and amplification for the other channels? Ideally, I'd like a surround sound receiver that has line-level outs for the front right and left channels, so I can use my integrated amp. for those, and use the receiver for the other channels. Unfortunately, I haven't been able to find one that has them. The closest is receivers that have pre-amp outs. But that would bypass the preamp stage of my integrated amp. even for music, and an inexpensive surround receiver won't have as good a preamp as my integrated amp. I'd like to spend $500 or less but will consider more expensive solutions.