Unless I'm missing something, an A/V receiver would replace your preamp. If you want to mantain a really clean signal chain for stereo-only music listening, you may use the Adcom preamp and amp. But if you want to use the stereo amp in a home theater setup, you need a receiver with preouts for at least the front two channels: this plugs into the amp in jacks on your amp. The vp150 and QS8's could then plug into the speaker output jacks on your receiver.
In this scenario, your receiver is acting as a preamp for all 5.1 channels, but it's only amplifying the center and rears. The only way you could still use your stereo preamp is if you unplugged the receiver front preouts and connected the stereo preamp preouts to the amp.
I would recommend the Harman Kardon AVR 330 or 430 receiver and the Denon 2200 or 2800 DVD player. I think HK receivers are still the most flexible in setup, though Denon & Yamaha products are also very good.
-Cooper
