I would try single runs of solid core copper.
I use 26 gauge for <12’ runs, but you could go down to 20-22 gauge.
I couldn’t find Neotech in 22 gauge (which I would like for a spare bedroom system I plan on putting together), but PC has 20 guage in stock (2 single runs per speaker).
There should be other less expensive option (just to try out).
DeKay
PS:
Just found it @ Sonicraft
https://www.soniccraft.com/product_info.php/neotech-solid-upocc-copper-in-teflon-22-awg-red-p-1587