1. From an engineering perspective, AKG did some cool stuff going on, but it’s also kind of hack-y. 2. See that bump at 3.5khz in the impedance graph and the peak in the THD+N graph? That’s a housing resonance. Most AKG headphones have this resonance at 2khz -- I believe they engineered this on purpose to utilize the resonance to tune the FR. Downside to this approach is that you can do it poorly and cause distortion…like the AKG K812 has. 3. Too many engineering trade-offs were made in this design, it could compete at $400-500, but it gets crushed at the kilobuck range.