Godling
Quick question from a neophyte...
Given the freq range of monitors, their responsiveness and how awesome they generally seem (kinda assuming this is why they're good in the first place?)... do people also use them for home theatre setups? Sure they're expensive, but if you can afford it aren't they better?
That works fine. It isn't all that common, but it works. When you start talking high end speakers, they all sound very good, are very linear, have low distortion, etc (well made ones at least). You'll see high end HT speakers used in studios. Abbey Road uses B&W speakers, for example.
Going the other way works just fine, most just don't because it is inconvenient. Generally you need a receiver to do your HT processing and those have amps in them. So using passives is cheaper (since you already bought the amps) and easier because you need only to run line cord to your speakers. With active speakers you need to run line level cables, which can need to be better engineered to keep noise out over long runs (since HT gear is usually unbalanced) and you need to run power as well.
You can get high end processors that are just processors, no amps, and of course you don't have to use the amps in a receiver, but it just isn't done that often.
If you do wish to do it, you just need to make sure that you either buy a dedicated processor like the Emotiva XMC-1 or you get a receiver with preamp outputs, which not all of them have (particularly lower end ones).