Will I benefit with 20 or 15 amp dedicated lines

I can't understand why you need a 20 amp when your gear only uses about 500 watts. 1 amp= 110 watts so a 15 amp circuit is about 1700 watts; a 20 amp is about 2200 watts, it is like using a 5 amp fuse when you need a 1 amp fuse. You are better off having a breaker trip instead of frying your gear. I know of no audio gear that would ever draw that much current,but if it makes you feel better go ahead and do it!
10-28-09: Yogiboy

The breaker is there to protect the branch circuit device, (receptacle), and the wiring... not the audio equipment plugged into it. The equipment has its own overcurrent protection.

As for the difference in cost between #14 awg wire and #12 awg the difference is miniscule. As I said in my earlier post most of the cost for installing the branch circuits will be labor.

And if by chance Kitegod would like to install Porter port receptacles on the end of his new branch
circuits he will be code compliant. It is against code to install a 20 amp receptacle on a 15 amp branch circuit.

Who can say down the road if Kitegod will upgrade his system. Maybe a bigger amp, or what ever.

The instruction booklets for both my Krell Amp and my JL Audio Subs recommend 20 amp dedicated lines. Go for the 20 amp line in case your equipment changes in the future.

A subpanel can have its own grounding, isolated from the ground of the main panel. I used 6 gauge for the ground, bolted to the center of a buried 2'x2' steel plate as is done for swimming pool installations.

For 20A circuits, 12 gauge solid core, not stranded, as a minimum should be used, but it all depends on the length of run. I did some overkill by running 10 gauge solid core for everything, which is not easy to work with but can be worth doing. Insist on the same size for the ground conductor. Twist the wires together using an electric drill before pulling them to prevent vibration in the conduit.

A subpanel can have its own grounding, isolated from the ground of the main panel. I used 6 gauge for the ground, bolted to the center of a buried 2'x2' steel plate as is done for swimming pool installations.
10-28-09: Essentialaudio

Not in the USA... It is a violation of NEC code. The feeder equipment grounding conductor shall be installed in the same cable or raceway and terminated in the same electrical panel as the feeder conductors.

I emailed Chris Johnson of Partsconnexion and designer of Sonic Frontier and he said the amp may perform better with 20 amp but 15 amp would be fine. He said the preamp is so regulated in the power supply that there would be no help with 20 amp.