There is some disagreement on whether or not there are some discrepancies in sound quality between different units of this headphone, perhaps different batches in production. They measured differently on head-fi than innerfidelity. Was some discussion on measurement rigs used. Personally I've heard them twice, really enjoyed them first time (though it was at a meet, a bit noisy), and found them to be pretty boomy and heavily encroaching on the mids the second time, which was at a smaller meet, less noise. Lots of variables there, but take it as you like.