Well, according to this ubiquitous Wire Table, for the 6 ohm QS8s, you should be using at least 14 gauge. It's not that it will sound better, it's that you don't want to cause a problem for your receiver. I don't know enough to say this is an absolute. Hopefully, those with more knowledge will provide more insight.

Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton