Besides my PC, I do not own any devices with the capability to control the playback of the Clip Sport.
I am amazed to learn this is possible with a car audio system.
I am wondering what would happen if you substitute a simple 16 gb flash drive (aka thumb drive) in place of the Clip Sport???
Also, I think 500 folders seems like a big challenge for the Clip Sport music database processor. And maybe even an excessive challenge for the car audio processor.