Time to make myself some enemies on this one...

I'm of the "wire is wire is wire" camp - except with one caveat - gauge.

Consulting a nomograph - you should be looking at about 10ga. wire for your run.

For a:
RL (load resistance) of 8 ohms
40ft run of 2 conductor copper
----
14ga. will give you a damping factor (RL DIV RS) of 40 which is low for home theatre (but fine for performance arena).
10ga. will give you a damping factor of 100.

What is damping factor? Here's what Marantz has to say about it.

Having said that... the driver size of the QS4s and their duty in the HT setup mean they don't need to be as responsive as your mains, but this is something to consider.

Bren R.