re: #60 Teukka

Only when you get to significant powers (≥250 W), long runs, and are close to the 6A/mm² at the same time, i.e. when you should be considering distribution amps and local amplifiers anyhow. Otherwise, 4-5 A/mm² is decent for ≤30 ft…

Addendum: I would be more worried about the inductive and capacitive kicks of long cable runs at significant power levels.