Todd - The extended length of the neutral conductor will not impact SQ at all - in the grand scheme of things, when you are travelling at close to the speed of light - a few extra feet is nothing.
What's more important in the helix design is the low capacitance and inductance and their ability to reject EMI/RFI.
You will notice that for the power cable and the IC's, the neutral conductor is thicker than the signal/live conductor - so adhere to that design point.
For Speaker cables I would try a high quality solid copper conductor of 14 gauge and for the neutral I would use two 14 gauge stranded standard quality conductors (equivalent to 11 gauge)
Keep me posted as to how you get on
Cheers
What's more important in the helix design is the low capacitance and inductance and their ability to reject EMI/RFI.
You will notice that for the power cable and the IC's, the neutral conductor is thicker than the signal/live conductor - so adhere to that design point.
For Speaker cables I would try a high quality solid copper conductor of 14 gauge and for the neutral I would use two 14 gauge stranded standard quality conductors (equivalent to 11 gauge)
Keep me posted as to how you get on
Cheers