Hi, maybe this is beside the point, but in my experience, there are no home theater receivers priced within reason, that will sound as good for 2 channel as your current Adcom setup. Well, maybe the used Krell HT separates. But you probably want a new receiver with HDMI and the new 1.3 for Blue Ray audio.
I used to have the same Adcom amp and preamp. The amp is still quite good sounding IMHO, but I think the Adcom preamp is terrible. I upgraded mine to a tubed Anthem Pre1 and was blown away. I agree with getting a preamp with the pass thru feature. A good preamp is the #1 thing I think for high fidelity. I think with a good 2-channel preamp you could get by with the power amp section of a decent receiver. But why not just buy a 5 channel amp? There is just no way to fit 5-7 channels of quality amplification (power supplies)and all the other hardware into a 40 pound 19" wide receiver. I suggest a 2 channel preamp with two outputs for sub flexibility as well. I think you are on the right track with playing cds through a high quality 2 channel player, and the excellent speakers. Sorry for the long post, but I myself am extremely disappointed with HT receiver sound for 2 channel. I would hate to see you spend so much to a take a step back. HT sound is just bump and sizzle to me.