Glad you liked it! Yeah, the songs are public domain music I got from OpenGameArt.org. It's a series of tracks called "Electronic" created by Alex McCulloch and the game cycles through the tracks at random.
Fun fact about that section of Level 3; the coins were originally one tile above the spikes instead of two tiles, but I wasn't able to get them consistently without getting hurt, so I moved them up a tile. Seems like that section might still be pretty difficult, though.
Thanks for the feedback!