How to set up REL Subwoofer?

How do you set up a REL subwoofer [R-205] as far as the connection? This is only for 5.1 HT, watching movies (BD/DVD) and HDTV broadcasts, not for music playback.

I haven't received mine yet and this is also my first 5.1 HT system/sub. Glancing over the online manual leaves me a bit confused. I thought subwoofers used a single phono cable, but REL supplies and emphasizes use of their Neutrik Speakon High-Level cable. Is this the connection most REL owners use with a HT set up? I also got the impression that you can, or should, use the phono cable w/ .1/LFE input in conjunction with it. The A/V receiver is a Marantz SR5004.

Thanks