To be honest I wouldn't trust Grado QC enough to even really give credit to these graphs as the average to what is expected. I guess they might have tweaked the drivers on top of changing the cups to aluminum. I still remember when the GS1000 was still a prototype and everyone shat themselves saying how good it was and then the production models became a huge flop and people suspected the prototype and production models were different. But then again people shat themselves saying how good the HD800 was before it was released and now the idea of it being picky with amplification or generally a bit bright or with slightly sucked out mids, lifeless, sterile, K701 on steroids, etc. seems to be more prevalent.