Adding receiver or amp?

Actually, I've had tube systems in small rooms, with the same challenges (and lack of ventilation, to boot). I personally don't see the difference between you using the very same system for music in that room, vs. HT! (unless you plan on blasting the HT system, and maybe drive the system harder and even longer than you would with music). Either way your system will put out heat!
Are you thinking HT dubties are going to drive the heat level and wear and tear of the system up exponentially at a faster rate?
Hummmmmm....I don't see the difference in all practical terms.
Your only other option is to switch to solid state (non-class A amplification) in that setup, with a tube preamp (if you wish to keep some "tube sound" in the system).
Actually, that could be a solution to examine.
Other than that, you're going to be trying to play the "dis-connect/re-connect" game with different pieces in your system, every time you wish to change sources/mediums - which doesn't make much sense.
No, the receiver route doesn't make that much sense, again, as you'd be swapping connections, amps, etc
I would be solving your amplifier/ventilation issue, and looping a pre/pro or receiver into the system, strictly using it as a "pre/pro" in the system - not for amplification.
Yeah, I would be looking to go SS for the amp, keeping a tube preamp in the system, looping in an AV pre/pro to an auxilary input on the 2 channel preamp, and adding a subwoofer to the system - for a 2.1 channel setup, yes! If you plan on building a more ideal set up, for which more guests can come and enjoy the system - seated around the room - then you can add another amplification channel (or use one from a receiver, yes) and center channel, for 3.1
I've done all of these scnearios, and it's fantastic!
Otherwise, get a separate
good luck

I have considered using my pre and power for HT, my "other" pre does have a HT bypass. but with 12 tubes in pre and 28 tubes in the power amps, they generate too much heat not to mention the cost of tube for movie watching. I know when I watch movie, my ears are shut off and quality is not nearly as important.

After more research and talking to my trusted dealer, I think the only receiver that will drive my Amati Homage comfortably is NAD785 and the megabuck receivers from Japan. My other choice is Emotiva which seems to be reasonably priced. I did hook up the Pioneer last night and hooked it up my Amati Homage and JL 113, the sound was more than acceptable as is. But once I add the center channel and surround (a friend talked me into getting surround speakers), Pioneer might run out of steam?

Yep, you have options. However, to keep it simple for your "integration" plan, I suggest adding either a receiver (looped into your "auxilary" or "Bypass" input), and maybe a center and/or rears and sub - connecting all those other speaker channels through the AV pre/pro (leaving your 2 channel setup basically "as-is"). In this scenario, you need to change out your tube amp for a good solid state one (or a multi-channel to drive ALL the speakers in your system.
It's actually been my experience, anyway, that the Sonus Faber speakers traditionally sound better with Solid state amps, anyway! (I've sold em and owned both the Electa and Minima Amators, which sounded ONLY good with solid state!)
So, you might consider.
Anyway, if you are trying to merge the two systems, this is my suggestion