Unfortunately most audiophiles have very little actual understanding of their electrical installation, so here goes:
When designing an electrical circuit we take into account several factors, overall current requirement, length of the electrical circuit ( this is more critical in radial circuits), where the cable has to run, so if within 100mm glass fibre insulation it requires a 50% de rating, does it run externally, does it go through a special zone (a bath room).
How many other cables is it running alongside.
It used to be, due to the cost of cable, the ease of installation and potential current requirements that rings were used as two runs of 2.5 t&e can safely cope with 32 Amps as a safety margin has been built in to these calculations. Theoretically a single run could manage without overheating 27 amps but this does not allow for all the other safety factors.
The dimensions of the cable 1.5, 2.5, 4.0, 6 & 10mm will change the impedance so a 6mm radial would be expected to have a lower impedance than a ring circuit in 2.5 t&e.
When we talk about impedance we are referring to the impedance of the live and CPC ( earth) as the impedance has to be within defined limits to ensure the safe operation of the safety device be that a fuse an MCB or rcbo.
The impedance we are talking about will have no effect on any equipment connected apart from operation of the safety device, definitely not sound quality.
I am struggling to re read on my crap phone so there might be a part 2.