Hi,

My Sennheiser CX-300 canalphones sound muddy and give off too much bass, regardless of the audio source. I'm pretty sure I'm putting them on right (by pushing them as far as they can go into my ears), and I use the medium-sized sleeves, which are the best fit out of the three included (though maybe not a perfect fit, because I can still toggle them up and down when they're inside).

For a while, I used the EQ on my Rockboxed iAudio to reduce the bass, but my iAudio has been damaged and I've replaced it with an iPod Video, also Rockboxed. And now I'm having trouble finding the right EQ settings again. With a little trial and error, this is what I've come up with so far:

eq enabled: on
eq precut: 30
eq band 0 cutoff: 50
eq band 0 q: 5
eq band 0 gain: -120
eq band 1 cutoff: 300
eq band 1 q: 5
eq band 1 gain: -60
eq band 2 cutoff: 2000
eq band 2 q: 5
eq band 2 gain: 30
eq band 3 cutoff: 5000
eq band 3 q: 5
eq band 3 gain: 15
eq band 4 cutoff: 18000
eq band 4 q: 5
eq band 4 gain: 0

Volume: -18 dB (with most of my music averaging at 94 dB via MP3Gain)
Bass: -6
Treble: -4

It's cut off at 50 Hz because I don't want a lot of sub-bass, and I don't think I can hear much beyond 18 kHz. I boosted bands 2 and 3 because words are a bit hard to make out otherwise. I don't know if the separate bass and treble settings make any difference when the main EQ is enabled, but I figured that they're worth a shot. I set the precut to -3 instead of just lowering the overall volume because it gives a slightly better sound, though I'm not sure why. I kept the Q values at their lowest because raising them seems to emphasize their respective bands too much.

The problem with these settings is that while they work well with electronica and hip-hop, and are okay for jazz and classical, most rock and soul music just doesn't sound right--that is, it's still a little muddy, thin (meaning that it doesn't feel like the music is inside my head), sometimes with unnatural-sounding harmonies on songs I'm familiar with, and worst of all, there's a ton of sibilance.

My goal is to make all styles of music sound natural by balancing out the quirks of my headphones, without raising any value to the point that it hurts my ears, and I can use all the help I can get from the EQ experts around here. Other than that, I'm wondering if they're simply defective and I could replace them with a better pair, or maybe if custom-made sleeves would fix this.