It is true that RG6 is a 75 ohm cable, however the LFE out/subwoofer line out that connects to a powered subwoofer is an analog signal, not digital. The RG6 will make things work, but would not be my first choice. If it's not possible to use a factory made subwoofer cable, then I would use a twisted pair with drain from Mogami cable and terminate with quality RCA's. Mogami quad 2534 cable would even be better, but it's a little more difficult to terminate.