I own the IE6 headphones, and I admit that while they sound good, they have a very colored frequency response. I remember seeing the frequency response graph at one point, but I can no longer find it. Bass and upper treble seem too emphasized. I've read reviews stating that the mids are forward, but that is the opposite of what I hear. These are really bassy and the high treble seems to be a bit emphasized compared to the upper mids and lower treble.
I did some EQing on my Clip+ based on what I felt was over or under emphasized. Mainly, bass seems well overemphasized, but I also noticed that electric guitars are recessed and isolated. They didn't seem to have their own proper space to shine, while drums and other atmospheric sounds had plenty of room to fill the soundstage.
Edit: [The following is what I originally did with the EQ on my Clip+. Check out the picture I link to after this paragraph to see what I've been doing in Winamp.] So, I bumped 4K, 2K and 1K while lowering 8K. I also lowered everything at 125Hz and below. This opened up the sound, taking away that bassy and tight sound that I honestly dislike if taken too far, which the IE6 does. Whatever I did still doesn't sound perfectly balanced, but it definitely sounds more balanced to me. The one issue is that the bump at 4K either seems to cause or shine light on occasional crackling in the music. I guess you could call them digital imperfections.
New EQ settings with Winamp and Equalizer 1.6 plugin: (original IE 6 frequency response graph on top, my EQ on bottom) http://i.imgur.com/bY1M6jf.png
The new EQ honestly makes the vanilla IE 6 sound terrible. With the vanilla IE 6, the bass is well over enhanced, and the treble is just so screwed up. I also didn't know of the huge void between 4K and 9K with the IE 6. That is a huge gap, and equally as bad as the bass bump. All in all, the humungous bass bump and humungous 4K-9K void are two of the biggest problems with the IE 6. Also, the bump at 4.5K is a major problem as well, and as you can see I fixed that as well.
With the new EQ, music sounds like it was intended to sound. Metal sounds LOADS better, as in I can hear each instrument clearly and naturally. Electric guitar sounds neither too bloated nor too isolated. It really blows my mind how natural it sounds compared to the non EQd IE 6. I never realized how strange the vanilla IE 6 sounded. It honestly is just a mess when not EQd, from 0Hz to 20KHz. Now, if only I could figure out how to use this EQ I made with my Clip+, which has a much more basic equalizer.
Edited by TrantaLocked - 9/30/13 at 3:40pm