Nah I'm not surprised. I've listened to a lot of NAD stuff and it has not sounded good to me. Only one product has sounded descent and that's the NAD 208 THX power amp but that's a really hit and miss amp. Some units are good many are not.
The audibility of these failings is highly debatable , much more likely are expectation bias that leads you to make these various conclusions. It would take direct A/B evaluations under tightly controlled, level matched conditions to come up with any supportable data.
That's not to say these measurements are without value and if examined closely could lead to advances in the SOTA.
Personally I find it disturbing that these units have revealed such a disrespect in the design of parameters that should be easy-peasy to execute in a much more respectable manner. Its a lowest common denominator attitude in R&D of much of todays units.
But before you stereo snobs turn up your noses and point fingers, look at how many very simple 2 channel devices have also turned in very poor showings, cheap DAC's and amps of which have been the worse offenders. The only reason for the exteme failings we have seen in the AVR's is manufacturers attempt of pack in so much, at such a low cost.
Amir, I encourage you to do your best submitting your results to manufacturers ala Atkinsons Manufacturer's Comments. I believe they figure no one is looking into such things and their secrets are safe. NOT.