However, not being an electrician, I’m having a hard time to picture having one or two lines with 6-8 outlets located in different locations?
First, my intent of my previous post was not to discourage you from installing multiple dedicated circuits.
As for feeding more than one receptacle outlet from the same branch circuit it is done all the time. The feed in and feed out wires in the outlet box are jointed together and pigtailed out for connection of the duplex receptacle. As for the wire connector used to make up the joints, connections, a spring type connector should be used. Example, Scotchlok brand made by 3M or equal as used in commercial/industrial facilities. Stab in connectors used in residential dwelling units are junk!, imo.
https://www.egr.msu.edu/eceshop/Parts_Inventory/datasheets/insulated%20electrical%20spring%20wire%20...
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I was actually thinking of 8/2 just for the amps.
#8awg? Must be some really big powerful amps. #10 is more than big enough. VD will not be a problem for your short branch circuit runs. I would be willing to bet the plug on the power cord feeding the amps is only a 15 amp plug.
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Since we are on this topic, what specific brand and model of the subpanel would you recommend?
First, copper bus only. Stay away from a panel with Aluminum bus. The problem isn’t that the bus is aluminum it has more to do with the bus breaker tie connection made to the branch circuit breaker bus tie connector connection.
I personally like the Square D QO series. It has copper bus. Stay away from the Square D Homeline series. It has aluminum bus and I don’t care for the branch circuit breakers.
How big of a feeder was you thinking about to feed the sub panel?
For house resale I would wire the panel 120/240V. Though you will/should still have all your audio equipment that is connected together by wire ICs all fed from the same Line, Leg. All from Line 1 or all from Line 2. Not from both.
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You need to find a good licensed electrical contractor/electrician to work with you. He will know what is required for local electrical code in your area.
Worth noting if an electrical permit is pulled there is a very good chance the branch circuit breakers in the new sub panel will have to be AFCI (ARC Fault Circuit Interrupter) type. Maximum breaker size for a 20 amp branch circuit is 20 amp, no matter if the wire is #10awg.
The electrician more than likely will have to install tamper resistant duplex receptacles for the final electrical inspection and then change them out to your audio grade duplex receptacles, after the electrical inspector signs off on the job. Ask him up front if local code for your city requires them. If yes then ask him if he will change them out after the final inspection. He may say no. He may not have any problem with changing them out providing you say you did it and not him.
Beats me why the manufactures of the audio grade receptacles are not making them tamper resistant for a residential dwelling unit application.