Okay maybe lengthening a cable is not a good idea. I just remeasured and my cable run is 35' so would 14 gauge be adequate? What I had ran before and this was several years ago was some flat cable but I can't tell if it's 16 or 18 gauge. Looking back I really should have ran a heavier cable even though I had plenty of volume out of the surrounds so I don't know the negatives of running a lighter gauge like I did if the end result is plenty of gain (unless it's something you just don't do).