12/2 is code in the states. Don't run an arc fault breaker or outlet unless it's a bedroom. They have a tendency to trip. Ground fault is overkill unless you just want the extra protection. Arc faults have to be on bedroom outlets now and ground faults in the bathroom and anything above the counter in the kitchen in addition to outdoor outlets. Commercial grade outlets are more than enough for audio outlets. We did not use any residential outlets in our home build. Bulk buying is the cheapest route if you need several. We wired the HT on dedicated circuits but probably not necessary with the new building codes. Also, in the states we were required to use tamper proof outlets with the new codes.
