Thank you so much! I'm so happy to see it in a playthrough! The crackling is being worked on, and the bass notes on disappearing platforms sounds awesome, so i'll look into that!
The crackling is likely due to clipping. My audio was on very low to begin with so I didn't get that. Sine waves mesh together and increase amplitude which eventually will peak what the computer is able to output thus creating crackling. Solve this issue by lowering the output each individual tone is at so when the chord plays they don't go over the headroom. Another possiblity is that your sine waves are not being cut at 0 if you are looping. Going from -10 to +10 wil create a clipping sound since you are skipping all the decibles in between.