Blue line is protein pads, which have solid pleather on the outside and the side touching the cheek, and perforation on the inside. Overall these pads bring down the upper mids and lower treble a little, ‘soften’ the sound to a certain degree. Upper treble above 10khz remains about the same though, and I personally would like this further lowered as the HEK V2 can occasionally get too hot here. A minor side-effect is the small bump near 1khz, not too bad though (around 2db).
the unheard of headphone lab 