Without equalization, as noted by others, these IEMs have a very high peak in the 2-4k range. When instruments are not playing in this range, they sound pretty good stock. Once you hear it though, it is quite unnatural/overwhelming. The best equalizer tuning I have thus far is attached - I had to completely bottom out 4k. The bass on these are pretty tight and exceptional. Typically I down-tune midbass for speakers/headphones. These have a weaker midbass, so I have left the 125-250 pretty flat. After tuning, I find them pretty impressive - I just can't imagine running them without equalization though.