We all like our pet sounds, and I'm not talking about goat feeding here (obscure joke of the week); I'm going on about what we expect when donning a pair of headphones. It may be related to a preferred genre, a previous pair which bit the dust, or a particular speaker setup. Maybe the term 'expectation bias' could be used here, or perhaps this is just related to what we are used to. A few years ago, I was quite into a bassy sound; I preferred bass filters with my Phonak earphones (yes it was a while back) and drooled over the original HiFiMAN HE-400 with its subby charms. Now, it's just a big wet towel which bungs the midrange up and hides those fine harmonic details. The Phonaks have treble filters now, and bass levels seem just fine. How did that happen? "Where's the midrange? I want my Aurisonics Rockets back!" This could be likened to wedding cake (it's OK, this will make sense). As a kid, I would eat the thick sugary icing and marzipan whilst leaving the fruit cake. Nowadays, I eat the fruit cake and leave the icing/marzipan since it's so intolerably sweet. I don't know why, but I'm not often invited to weddings any more. So if newly aquired headphones do not meet the beat (or beat the meat), then give it time. Rather than sending them back immediately, give them a few days and try to focus on other parts of the sound such as textures in vocals, midrange harmonics or a certain sense of space which is lost on bassy headphones. However, if higher frequencies are causing sibilance problems with sharp 'ss' sounds then you will not get used to those. We all have a certain sensitivity to these frequencies as individual as our shoe size, and if it's hurting then you'll need to try something else.