The staticky noise is caused by the way the game compresses the sound files, I think, and it is much more noticeable when you have a song that has times where there is silence and no instruments playing in the background (note with static over it -> complete silence). Have you tried using this? edit: circles posted it.
If that patch doesn’t work, the best way to make the static less noticeable is probably to have a very quiet instrument playing in the background during parts where there is normally silence. That should make it so the noise in the background is playing all the time and the player’s mind tunes out the noise, instead of “oh, suddenly everything is silent and I’m hearing the noise as soon as anything plays again”.