The A/C background sound has a very audible "click" every time it loops, and it's especially noticeable because the sample lasts less than 2 seconds. As the game is apparently abandoned, I guess it will never get fixed, so here's what I did to get rid of the clicking:
- From the game's "assets" directory, load "ac_good.wav" in Audacity.
- Select -> Select All (Ctrl+A) to select the whole track
- Select -> At Zero Crossings (Z) to prevent the click while looping
- You can hit Shift-Space to listen to the loop and make sure the click is gone
- Use the Trim tool (Ctrl+T) to drop the bad bits and the start/end
- File -> Export -> Export as Wav

I did this for all ac_*.wav files. (Keep a backup of the old files just in case.)