I find this discussion of T758 V3 an interesting case of how bad something can measure and still sound good which I think is important since how something ultimately sounds is the point. If it sounds good to you, I don't think anyone has a problem with that (I know I don't). But a few random comments from my perspective...
-I have owned the T758 V3 for about 18 months. I really do like Dirac. However, I was curious how it would test, so I bought a second one (new with the updated board from safeandsoundhq.com, which by the way are great to deal with). I don't think there is any reason to think it was defective. In addition to @amirm much more extensive testing, Sound and Vision also did their normal bench test which was also pretty poor it looks to me (link). I also attached the Denon X7200 for comparison. I don't think there is any reason to think it was defective, it just measures really, really bad. You don't need a 40K receiver (is there such a thing) to perform pretty well.
-It is great that the poor measurements aren't audible to you. It has Dirac, has a lot of features etc. But I do take issue with comments that say this really poor measurements of both the DAC and the Amps aren't audible... to anyone, at any level. That is a pretty bold statement that I just think is way over the top. I wouldn't be surprised if quite a lot of people would be able to pick on on that noise/distortion caused at those levels. Those measurements are pretty crazy bad.. In my theater, it sounded good to me (I do not have golden ears by any means) at moderate levels but found that after a few minutes I would always have to back off the volume to around -15 despite wanting it louder. Never gave it much thought until after I saw the measurements. I also moved the unit from the theater to our living room (much noisier environment) and an untreated room, and again found it sounded fine with volume from -15 to -25 on the volume. So while it sounds great to you at all levels, it doesn't to me in my setup at louder volumes.
-For $1499 ($1000 off) you can now get an Arcam AVR390. I couldn't find a bench test for one but looking at their other models it seems they measure relatively well and don't have to deal with the issues of the T758 which will be an issue for some people.
Just a few thoughts from a soon to be former owner. YMMV of course. It is just a receiver, so I don't get worked up about things and am happy that you are enjoying it. Carry on
Yes, maybe others can hear distortion. I did not, but only tested at 0 dB, I didn´t go further as my ears couldn´t bear such a loud volume, and also was afraid to blow my speakers. And maybe, just maybe, you had to lower volume due to the harsh highs that DIRAC sometimes configurates, and needs from you to perform a few tweeks to tame them. Try the NAD curve, it worked in my room.
And yes, NAD could have engineered a better AVR. At a higher cost I guess, but still.
Finally, a guy at AVS (@Markus767), that practically solved all initial issues with the T758, also tested the Arcam and found serious errors in the bass management implementation of that AVR. Can´t comment anything else, as I have never heard that device. Would be nice if Amir could test it. At $1500, it seems like a very good deal too.
Regards.