Ok. I thought ity was about time that I weighted in on the "Class D Controversy".
First and foremost, NO DAMAGE WILL OCCUR IF YOU DO NOT USE THE "DIGITAL" CABLE WITH A CLASS D AMP. I just won't sound right, or won't work at all. Case in point, Sony Digital Direct Drive amps won't work at all without the special cable. But, Pioneer Elite/B&O IcePower equipped receivers work without any special cables. Some Class D amps will produce a garbled output from the woofer. To my knowledge, not a single amp or woofer has failed that can be directly linked to the REL hookup. If you have your REL hookup up now and its output seems normal, then you are OK.
The Digital REL cable is not just a standard REL cable with an RCA for ground. It actually has a set of specially selected capacitors to isolate the ground.
I spoke with Kendra and the 'up in smoke' comment was just a joke. Obviously, it was not taken that way.
Also, on a related subject, Class D amps are not necessarily digital. Also, most are not differentially balanced. The description given earlier is not accurate and should not be used to determine what kind of amp you have.
AND, the 'balanced' hookup on B-series HAS ABSOULUTELY NO BEARING ON CLASS D AMPS. It was designed for systems with 2 RELS in stereo using differentially balanced mono-block amps, so that the RELS can operate in a push-pull fashion just like the amps. I've tried this hookup a couple of times, and still prefered the standard hookup anyway.