The PuriFi modules in the M33 are as load-invariant as one can get. So I would concentrate on the basics: low R, L, C in the cables. That said, Blue Jeans will make some up for you with Belden wire that should be great.

You will get advice to pay hundreds or thousands for boutique wires. Such wires sometimes sound different -- they are designed to sound different -- but they will not be more transparent or neutral. If you want tone controls, I'd suggest using the ones in the M33.