What the chart is saying is that, with 6 ohm speakers, and using 16 gauge wire, the maximum run you should do is 37 feet. If your run is longer than that, (45-50 ft.- possibly longer), with 6 ohm speakers, you should be using either 14 or 12 gauge.
I am not technically oriented enough to say how absolute that chart is. Maybe JohnK will chime in tonight, with more help.
I'm a little confused. You say the BACK surround runs of 16 gauge wire that is in your walls is 30 to 35 ft long, and will be used for the BACK surrounds. What speakers will you be using for your BACK surrounds?
But, you have a 45-50 foot run to your QS8s. I'm assuming you will be using your QS8s for your surrounds, NOT your back surrounds. If that is correct, use some 14 or 12 gauge for the QS8s.
