NAD C316BEE V2/Subwoofer dilemma…

Sounds like the person at the "mail order" outlet you bought this from is not all that knowledgeable.  With that NAD amp which has an internal, common ground it is just fine to connect these amps via speaker level inputs. 

For others who might read this thread, you do need to exhibit some caution as some dual mono designs and obviously mono blocks can be an issue.  You don't want to create a common ground in the sub between two amps.  This will negatively impact your day and at best, you will be searching for fuses.   

Thanks!!

The “how to connect” info on speaker level inputs in the sub manual should’ve been a research item of mine early on and It’s answered every question I’ve had here!

Read the instruction manual!

The high impedance of the subs internal amplifier allows for use of the NAD speaker outputs for the sub as well as for the main speakers.

That’s what I was thinking (that the speaker level inputs on the SVS would make everything a simple matter)…..The monkey-wrench-in-the-gearbox (or not??) seems to be related to the NAD’s lack of any pre-outs coupled with having only connections for one pair of speakers.  I don’t know if there’s a workaround…

That SVS has speaker level inputs so there is no problem hooking it up !