This is another classic -- always fun to watch the back and forth.
This issue can be broken down into two separate areas.
1. House wiring safety. What size wiring needed is determined by the amperage of the circuit breaker used for that circuit in the panel. A 15 amp breaker needs 14 gauge wiring or bigger. A 20 amp breaker needs 12 gauge or bigger wire. Note that the electrical code contemplates that continuous use of the circuit (hours or more) won't draw more than 80% of the circuit's capacity. (That's why electric car charging circuits require a 40 amp circuit to power a 32 amp charger for example.) The code is mainly concerned about you not burning your house down or shocking someone.
2. The other issue is audibility. Many audiophiles suffer from the disorder that "if this much is good, more MUST be better." Combine that with our psychological ability to hear what we want to hear and some will not be happy until they have 4 gauge wire all the way to the socket on the back of their gear.