While I don’t recommend it if you have the opportunity to do better, but I thought I’d offer this information:

I’m running all the gear on one 15-amp circuit, including an Outlaw 770 amp and two subs that could potentially pull 600 watts each. I can raise the volume to ear ringing levels without tripping the breaker. So, six circuits may be near overkill if your needs are not great.

If I were constructing a room from scratch, in addition to enough mains power to meet future needs, I’d run conduit for audio/video/data cables/fiber anywhere they might need to go. This conduit would never be for power, and would allow the use of cable not rated for in-wall since the cable will be entirely within conduit while in the walls or ceiling. The conduit would be the largest diameter practical and with the most gentle curves to aid in later cable pulling. Within all conduit runs, I’d also leave some strong pull-line for future use. Later, when pulling in new cable, also pull in a replacement pull-line.