Will I benefit with 20 or 15 amp dedicated lines

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.

Bill, you can use either 20 or 15 amp breaker, just be sure to use 12GA wire in your new dedicated circuit. Most electricians will use 14ga wire for a 15 amp circuit.

One other thing to mention too. Before you plug the breaker into the panel, look and see which side or leg your kitchen frige is on, and select the other side or phase. no point of going to all that work then pulling power off the same leg your fridge is on, introducing the motor noise into your gear.

You may also want to look into a dedicated ground, which will remove additional noise, but just make sure you issolate the ground from the rest of your house.

You also did not mention how hold your house is, but many homes built in the 80s used the outlets where the wire can be pushed in from the back. Don't use those. Make sure the screw terminals are used so you get a solid connection.

best