Well, we'd fuck less with the FR, if mfg's would churn out less sucky phones. As for HD600/650 it sometimes baffles me how it is so that no other mfg has made anything that's as neutral as these phones. And judging by some of Sennheiser's later headphone releases, even they might've got lucky with these. I know that head-fiers like to bash speaker dudes about how cans offer that room uncoloured sound for a fraction of the price of good speakers. Yet headphones usually have far grosser and more unpredictable tonal inaccuracies than the majority of half decent speakers. You've done your fair share in speaker building, you should know!