Mp3 distortion

I download mp3s from several free sites .mostly indie artist but some well known. Upon playback or after burnin to cd (Nero 6.6) there is peak distortion on high notes and certain other freq’s. Can really hear it on ambient stuff. Adjusting overall vol is not the solution. sounds like somethng can’t handle certain freq’s and distorts them. Any ideas? getting very very frustrating.

Such free MP3s are typically low quality, 128kbps encodes. There is nothing you can do about it.