Is it damaging? Balanced amps & high-level sub input

@kirkwallace great info and thanks for sharing your experience sir. I just received an email from one of the village elders at TMR, he said to connect both the positive posts, to both positive high level inputs, not one of each +/- , for say the left side. I’m assuming for the same logic, that the negative is tied to common ground, and imperative for signal in balanced topology. 

@jbuddha882 i’m not following your last sentence, but it is probably my fault not yours. I would follow what the TMR person said. 

My last sentence was an almost exact quote, or exert from your original post, so I’m not sure what you don’t get? Like the REL rep stated, the negative binding posts are connected to the amps common ground. So ie leave those, untapped. 

Sorry, but that it not at all what the REL sales manager said. If your amp is balanced or Class D, the negative speaker posts are not connected to ground. In my case, the guy who designed the amp confirmed that the negative post was connected to ground, and in that case you connect the black wire to it, but that is not a general rule.

Well this thread just gave me a sick feeling.

For years I have had my Hypex based Marantz Ruby integrated connected to my HSU subs using both the positive and negative speaker terminals for many years.  Same with REL subs.

How in the world did this not damage my amp??

Addendum:  I may have found my answer.  AI initially stated the Ruby had a floating ground.  Re-asking the question based on output topology, it said the Ruby uses a single ended hypex module which is tied to a common ground.

Whew!!!!!!!!!