REL speakon connection to amp vs speakers

Sorry if I am missing something, but if Signal Cables is using REL cable, how is there a difference between the original or upgraded REL cables (Bassline Blue) and the Signal Cable? 

Are the connectors different?

a number of manufacturers make their own version on the "REL" Cable...

@pbomberg 

Funny you should ask.  I spent some time last weekend making some custom cables for a pair of REL subs I just bought.  The subs are to the outside and just a bit behind my speakers, so it made sense to make a short cable to hook up to my speakers, not the amp.

The result?  Dead silence, no humm, great integration.

And , yes, the manual is very poorly written (or NOT written) for stereo subs!  Good grief REL.  You can do better.

I have never had hum with my REL S 812’s, but have wondered if leaving the Speakon ground unattached to the Audion monoblocs might confer some subtle improvements in addition.

 I have not found any difference between connecting at the amps vs speakers with my pair of REL T5x on several different amps except for my Naim. For some reason the volume output was reduced when connected at the amp.

 With stereo pairs, REL recommends placing the subs next to and slightly behind the front of the speakers. If you place them like this you can use a shortened cable to the speakers, rather than one that has to go all the way back to the amp.