stacking speakers?

I overlooked Sean's good point. I assumed the monitors would be removed when not in use. Resonance is more likely to be a greater problem for music than HT in your situation.

but you can turn on the amps driving the speakers not being used, and the inaudible hiss that is barely exiting the non-playing speakers will cause it to not respond nearly as much as it would otherwise, almost eliminating the problem. it's not an ideal solution, but it can help.

I also agree with Sean's point of reradiating, not a good idea to have a "live" pair and a "dead" pair stacked. If you can't move them, the next best thing would be to get a sound-deadening cover or wrap, for the pair not in use. This may not be perfect, but is alot better than the free interaction you get now, and it may be more convenient for you to not move the speakers around. Removing them from the room is a better solution though. While on this subject, when working in a high-end audio shop, we did a fun experiment. We allowed customers to audition a speaker, and then without telling him, we then brought a cordless telephone in and set it down on the table, facing up. We acted like we had just finished a phone call and were just putting the phone down. We then played the music again, and invariably they would comment that the system didn't sound right. We used this demonstration in a "blind" way, to show the customer the effects that even a small speaker in the room can have on the sound. TV's, small radios will all have some effect. Eliminate or cover all dead speakers in your listening area and you will have better sound.

Uh, call me crazy, (and I assume you have a good reason) but if your HT and 2-channel systems are literally stacked on top of each other, why not use the same speakers for both? Am I missing something?

Thanks everyone for the great input and advice.
I'll try out the differnt options and see what happens. O.k. Mezmo, I'll call you crazy. Just kidding. I did at one time have all the speakers hooked up to my HT system, Then I found the joy once again of 2-channel audio. In novice terms ( That's me, the novice) the music sounded better in 2-channel, then it did in surround sound. Having four front's and a center facing you, didn't sound any better then when I seperated the speaker's.
I would have placed the bookshelf's to the sides for a more complete surroud effect, but for one problem. My wife, and I qoute" your not going to be spreading your speakers all over the house making it look like a stereo store" end of qoute. :) Thanks again everyone.