Glad you asked!
As far as settings are concerned, I was using the hdmi output from the Oppo to the AVR, so there were no speaker configurations applied at that end (verified in the owner's manual).
In the NAD setup, the menus are relatively simple and I checked every possible speakers setting to include the size of the speaker, the distance, the crossovers, and of course whether or not audio would be output for that particular channel.
One of the downsides of this particular model is that I dont have complete control of all the eq settings etc because it was meant to be a simpler interface. I prefer in depth settings, being a technical guy in the army and everything. One of my favorite past times when purchasing new equipment is going through every possible setting to make sure that I know the device completely. Oh yeah, and unlike most guys, I tend to read the manual too....but I digress.
As far as your other question, I do not have another AVR to try. I do however have two more speaker outlets on my stereo amplifier, so I may try to hook the sub up to it via the high level inputs. But that doesn't really provide and end all solution to the problem becuase I would be using a completely serperate input on the sub. I prefer the RCA input anyways.
I am also inclined to agree with your assessment of it simply being a matter of a weak signal given off the by the NAD. I will have the repair technician check that out to when they receive it for repairs.
