Used to, yeah, but its been a while. Its a bit expensive, but you can find the black in smaller spools. Colors pretty much require a 300m spool though, which is like 600 last i checked :/
Canare/Neutrik is a fairly common studio standard. Mogami (the nice stuff, not their cheaper stuff) is good too. The nice thing about the Canare GS6 is that while its designed as a guitar cable, despite its super low impedance it has the gusto to handle high power situations, and is perfectly safe to use (cant comment sound wise, as I've never done it) as speaker cable.