In ,
Stewart Pinkerton typed:

12 AWG (which is indeed about 3.3 sq mm) copper wire has a linear
resistance of approximately 1.6 milliohms per foot, giving you a loop
resistance of about 52 milliohms for a 5 metre cable. This should be
between 1 and 2 % of your minimum speaker impedance, so not a problem
by any measure.


Yes, most likely overkill, but a small amount of extra cash compared to the
overall cost of a system.

Jo