Try checking your DSP studio settings and compare them with those in version 24.
I had a similar problem with I updated from version 21 to version 28 - rather than "pops", I was getting some "snaps" (like a whip snapping). I also lost a lot of bass. After I went through the DSP settings I finally got pretty much what I wanted. Most of the "snaps" had disappeared while my bass was back to something I could live with.