For interconnects, I’m using Belden 1694A, new cable when I constructed the interconnects, rated to 3GHz for Digital Video, with Canare crimp-style RCA connectors. Shouldn’t lose too much at under 50KHz!

For loudspeaker cable, I’m also using video coax cable, this time surplus Belden 8281. I’m not using the center conductor at all, just the two-layer, tinned copper braid shield. This dual layer braid has a DC resistance equal to about 11 gauge solid copper, a very decently low resistance. A speaker at 50 feet would require the signal to make a 100 foot round trip. Using this cable, the current traveling to this speaker and back experiences only a 0.11-ohm resistance from the 'coax speaker cable.' Using only the outer layer is like running the current through a flexible, insulated, tinned copper pipe so there’s no current trying to flow where even the very small back EMF would concentrate in the center of a normal conductor. Even though this is a somewhat stiff cable, I think I've gained the benefits of some more esoteric cable but for a low price.

Have I gone a bit overboard? Probably, but I spent less than twice as much as buying off-the-shelf RS interconnects and medium gauge zip cord and I think I’m getting very near higher-end performance.