Years ago Cardas made cables for single ended amps and/or hi-eff speakers. They called them the SE-15, SE-11 and SE-9, the numbers represented the gauge. What I found interesting about them was how small they were in diameter. I would expect that from a 15 gauge but even the 9 gauge was skinny, about the size of an 18 guage ac cord. I believe dielectric absorption can be a factor in the sound of cables so maybe Cardas was on to something with their thin insulation. These were copper btw.
Single ended amps are capable of rendering such small details clearly, it would be a shame to "smear" them with a delayed signal. As far as conductors: Silver conducts better than copper and you can coat the silver with Teflon, which has a very low DA factor.
The best cable I've found for my SE amp/hi-eff system is a fairly skinny Teflon coated silver wire (no brand name, made for me by a friend). I can see why Markus1299 and Charles1dad like their cables so much with their systems.
Silver can be pretty expensive though and if you want to try something cheap, that I think sounds pretty good, go to Radio Shack and get a 60 foot spool of their "18 ga Stranded 2 Conductor" speaker wire. They may have smaller lengths but the 60' was only around $20. I have thicker "name brand" cables laying around but prefer this for what we are talking about. It has the thin insulation due to it being "only" 18 ga and has 6 or 7 strands of copper which I think is better than 200 hair like ones.