[jimbo2012]

Without question, the 3 gang box.

First cut the drywall where the box will go.

You have the right idea #14 romex find the top plate in the attic drill or punch a hole depending on materiel, if metal stud on top install a plastic chafe guard in the hole.

then run all other wires including speakers etc.

Run the romex to a 15amp breaker.