I think you may have just demonstrated your lack of understanding of how a driver works. I touched on it in the first post, so I'll begin where I left it. A transducer reproduces sound most accurately near it's resting state. This means that small amplitude vibrations are clean. The further away the diaphragm gets from the center, the less linear it gets and consequently the more the sound distorts. I think so far we are on the same page. So here's where your logic is failing - it's a fullrange driver. At the same time as it plays the lows that push it far from it's comfort zone, it simultaneously plays the highs, that are being reproduced in and out of that comfort zone. The small, high frequency vibrations are subjected to the same modulation of forces as the bass. This causes often audible distortion throughout the range.

The reason why opinions like the above circulate is because many people learn from basic theory and looking at graphs instead of using reasoning and insight. The distortion that you see in reviews is a so called THD or total harmonic distortion. Let's break down this cluster. HD or harmonic distortion is a measurement. It's not a physical property of a driver. It's an oversimplified measurement procedure that is older than sound reproduction itself. It wasn't adapted to your psychoacoustic model, and neither does it describe accurately the troubles of reproducing music. It is simply playing a SINGLE tone and seeing what other tones come out. Total HD is simply a way of presenting this data in even simpler form. No wonder you don't know how a headphone works, you're basing your knowledge on a simplification of an oversimplification. Real distortion test that's representative of sound quality is a multitone intermodulation torture test and a set of compression curves known from Klippel. There are plenty probably other flaws in your concept , but let's just stop and digest this. IMO the OP makes a great point. The basic measurements that we use dont fully describe sound quality. It may be enough for you, but that's just like your opinion, dude.