Very cool game! Combining rhythm game elements with those of a tower defense game is such a cool idea, and its executed quite well here! Graphics and audio are both really strong, too.
Just a couple of nitpicks: I think there might be something off with the space bar turntable because I had to press the space bar about a sixteenth note after the beat for it to be timed properly. The audio balance was good overall, but I noticed that the sound effects could get pretty loud when they stacked on top of each other, which made the music a bit harder to hear.
Besides that, really great job with this!