tigon_ridge
1000+ Head-Fier
He may have been referring to the peaks around 7-10 kHz.
Running frequency sweeps with all three Lambdas I had, this was the area where it got the peakiest, so to speak.
The overall frequency response is so linear that this isn't an issue for me. (And it's easy to fix with EQ.) If the peaks were at 3-6 kHz (which is common with other tech), it would be a different story.
I've said it before and I'll say it again. Digital EQ is the most underappreciated, underutilized, and least understood aspect of all of hi-fi/audiophiledom/headphone community. People who are just wholly ignorant of how much good a nice digital parametric EQ can bring to the enjoyment of their expensive (and not so expensive) audio gear. AND IT'S FREEEEEEE! Instead, you see audiophools all over who shell out big bucks for cables that they admit have very little audible effects on their audio chain. These people don't even bother to post results of a proper ABX comparison of their cables (probably because they haven't done such testing, or have no clue what it even entails).
People don't understand that literally every pair of headphones requires some EQ to sound optimal. For one thing, they all come with a certain amount of channel imbalance at varying frequencies. Imbalance at sibilant frequencies is the most annoying thing of any headphones, in my opinion, and sometimes headphones come with them by default, and there's nothing you can do about it, except balance the channels using EQ.
People also assume that manufacturers meant for their products to have their exact frequency responses as what is measured. It's completely asinine! It's incredible difficult to have ultimate control over response curves, and manufacturers merely do their best to adhere to stay within certain parameters. If you look at the 009's response curve, it lacks that 9k-10k spike that other STAX headphones have. Hmm, couldn't be one of the major reasons why it's STAX's flagship, could it??
One may prefer headphone A to headphone B, but after some EQ, one may prefer the complete opposite.