When I did my dedicated HT in my new condo about a year ago, we put in 5 seperate circuits.

1-20 amp for the three front speakers, all of which have powered subwoofers built in.

1-20 amp for the Outlaw 770 amp. (I would probably do this different, knowing what I have learned through this forum, if I had not already owned the 770, and have a couple dedicated circuits feeding the 3 front channels and the surrounds on seperate amps. But, the way it is done works pretty well.)

1-20 amp for the front projector.

1-15 amp for the rest of the equipment.

1-15 amp for all the rest of the general outlets in the room.

Regardless, of how you go, be sure to keep your power cords separated from your a/v connectors.

Also, I'd use separate serge protectors for your a/v equipment and amps (if you aren't utilizing a receiver.)

These last two items will go a long way in minimizing the opportunity for ground loop hum.

Just my thoughts. It isn't cheap, but it's a lot less to do it right now, as you obviously already know. I'm sure there are lots more ideas out there in this forum from people who are a lot more technically astute about these issues than I am.