I think channels it the right word to use. To give an idea of the issue, on "Eleanor Rigby", the singing in the verses is very quiet, and in "Positively 4th street", the organ is barely audible. This is only in a few songs though, and it's only when I listen with headphones (haven't tested yet if different headphones will work properly). The sound is normal when listening to the phone speakers. I've only had the phone a few days. Is this a common issue? What might be the problem? The headphone jack? The headphones? A software glitch? Incompatibility with the sound files for some reason?