Actually thinking about it, when you have more individual drivers to play a specific frequency the separation in your audio is better therefore you get less interference from neighbouring frequencies. So by adding a sub you have gained more depth in your tracks. Another point would be your source of audio, and the files you play, if you're listening to compressed files like apple music then the stock stereo after EQ'ing would be adequate. Also, if you like your music loud, distortion will be an issue so any named brand premium audio should reduce that as they're using bigger drivers, which will distort too but at an uncomfortable volume. Sound signature, if you're into your bass and volume then it's worth the price but if you're into a natural - flat EQ I would say, save yourself the money and buy a decent set of personal earphones. Sent from my iPhone using Tapatalk