[clpetersen]

I have a pair of REL T7i's in our media room and very happy with them.
I had them set up two ways - in the back corners and now in the front corners. Both worked well with some attention to trim, phasing etc.

Cables: To run them in the back, I needed more than the stock ten meters (running under floor around perimeter of room). Called (emailed) REL and they were helpful. Built my own, using standard speakON parts and 14 gauge Belden twisted pair (unshielded). 14 gauge is complete overkill, but added little to the overall cost (since running in stereo pair, needed only two wires per sub, and jumped inside the Speakon end)
REL stock cable is basic but adequate (excepting assembly errors). It takes the voltage from the very low output impedance amplifier speaker terminals (typically < 0.1 ohms) and delivers to the high impedance (150 kilo-ohm) REL inputs. Meaning it carries almost no current and is effectively shorted at the speaker ends, making it largely immune to noise pick-up (e.g. 60 Hz hum, etc.). Smart.

So, in this particular case, a well assembled, good quality but straightforward cable will be all that is required.

(in the front corners, I use the original REL cable, shortened (cut) to 4 meters).

For anyone else contemplating a customized REL cable.