An odd idea

One of the regulars on this forum who is also an electrical engineer can correct me if I'm wrong, but I think that having your speakers connected simultaneously to two amps -- even if one of them is turned off -- may produce an undesirable electrical interaction. The electrical signal coming in from one set of speaker wires can still feed down the speaker cable going to the unplugged amp (assuming both sets of speaker wires are connected to the same binding post), which can lead to anomalies in the resistance/impedance, and may even produce undesirable EMF (electromotive backforce) similar to the current produced by the rearward movement of a speaker cone.

In short, even if one amp is always turned off and you NEVER make a mistake of leaving both amps on, this is probably a very BAD idea from both an electrical and audio viewpoint. I'd recommend doing what I do, and what others above have suggested: use a 2-channel amp for your main speakers, and a separate 5-channel amp for your center and surround speakers

One thing to remember about Home Theater is that there really is no 'reference' standard. Unless you have precisely the same speakers for Left, Center, and Right, channels your center channel will sound different than the others. In home theater, much of the sound comes out of the center channel, so you might want to upgrade your front three channel amplification (just a thought).

The other thing about home theater is that DVD recordings/sonics are not that good when compared to two channel audiophile recordings. Having speakers that are matched gets you 98% of the way there for good home theater balanced sound. Amplification is almost a secondary concern per se. What a better 2 channel amp will give you that you probably will notice is better bass response in the front two channels. I run 7.0 channel sound with my two channel system driving the L and R channel. My L, R, and C channels are all matched (Vienna Acoustic); however, my rears and sides are from a different speaker manufacturer altogether (Acarian Alon). The sound still is truly amazing. My L and R speakers play so low (22hz) that I have no need for a sub.

If you want a large leap in performance from your Rotel without breaking extreme budget, I would suggest going with something like an Aragon 3 channel amp used. Another option that could be very good would to be going with Monarchy SE100 monoblocks. I once drove a complete HT system with Monarchy monoblocks. These little amps sound awesome and are very good deals used.

There are a lot of ways one can go with amplification.

What I would not worry about is the different amplifiers driving your speakers. YOu have matches speakers, and that is 98% of the battle.

KF

NEVER feed one amp's output into another's! The output impedence of the "disconnected" amp is MUCH lower (0.1 ohms or less with ss) than any speaker, and you'll quickly blow up the unused amp, right?

Unless you feel your system is lacking in dynamics or sounds like it's straining at your listening levels, you might not want to replace the amp just yet. There are a bunch of tweeks you can to to the typical H/T setup to improve performance. The first would be to adjust speaker location and make sure there is plenty of room between the TV and L/R speakers. You may even have to move them forward so that they are not on the same plane as the TV. TV's are bad for sound and the bigger they are, the more problems they cause. Even better would be to get a plasma and get rid of the box altogether.
You could also try is getting new CD's. One reason people are happy with home theater performance is because movie soundtracks are recorded at a higher sampling rate and sound much better then your typical CD. But there is alot of variablity even amoung redbook cd's. Look for newly remastered copies, HDCD's or enchanced versions of your favorite songs, DTS cd's, or even DVD video. I wish there was more out there in terms of multi-channel audio because the sound really is fantastic.
As a last resort you might want to consider a tube CD player. Some people like the tweekability aspect they provide, but i personally never found them to improve the sound as much as finding a better recording.

Again, thanks to all for the suggestions!

Tok2000, you make a good point . . . . I guess the speakers are the key, moreso than the amplification.

Subaruguru, thanks for the warning!

Perkadin, interesting suggestions! My speakers are already set up as you suggest -- about 2 feet out from the TV (any farther and they are too close to the side walls) and about a foot in front of the TV. I hadn't considered the CD quality issue, though . . . . and my system is definitely not lacking in power or dynamics. I've thought some about the tube CD player idea, too.

I think what I'm going to do is finish all the tweaks I can with the existing hardware -- install the 2-channel passive preamp, upgrade the 2-channel path cables from Audio Ones to Audio Twos, upgrade the power cables on both the 9000ES and the Rotel 985, and apply some isolation/damping treatments to both -- and try to isolate what I feel are the system's shortcomings in a little more detail.

I also want to play around a little with some room treatments -- I don't know much about that, but I figure that there's no shortage of places on the web to learn.

THEN, if I decide the new amp is a necessity, I'll pick one based on what I want for 2-channel, without worrying too much about HT integration, since I know that a) it should work OK, and b) I can always go with seperate speaker cables if it doesn't.

Again, thanks much to all!

Pat