Dedicated power

If lights are 'blinking' they are on the same circuit. Sockets and lamps should be wired on separate circuits. Likely there are other high current loads as well.

I've been doing this a very long time. Including professional recording studios. 12ga wire and 20A breakers for walls of amplifiers. Main monitors typically 1 x 20A circuit for 4 x 500 watts [250wpc]. Playback on STUN didn't dim the lights [on a separate circuit] or jiggle a peak responding line voltage monitor.

On a 14ga 15A circuit with 10 foot run to the socket, I currently have tri-amped speakers - total 315WPC - plus 2 subs 300W each. Speakers are ≈84dB/w/m and peak levels are +100dB. The REAL cannon in Telarc's 1812 barely jiggle the line voltage when measured with a DSO. Amplifier outputs scale to input levels, i.e. NO compression.

Talked with my friend who is doing the wiring. We are gonna do 220v to a small box very close to where the outlets are going. This should distance the circuit even further from other crap on the lines and only cost about 50 bucks more to do. 
We did determine today there is gonna need to be a bit more drywall rip up than we initially thought. HATE HATE doing drywall! Ohh well crappy patch job and hang a pic over it.  

The lights are wired on a separate circuit, it was a 2800 watt sunfire subwoofer, playing telarc time warp. I've seen lights blink in too many different systems to believe it could just be dirty connections. It has to be voltage drop on the line.

The feeder line from the main service panel to the sub panel is 65' and it's 2awg. That same sunfire sub did the same thing in my friends system and the circuit was only 20' from the main panel.   2800 watts is quite a bit of power.