You can use the app to customize your sound by, say, boosting the bass.

Bass is just average and can be boosted with the jaybird app which helps some.

I love a heavy bass and that is certainly achievable with the range of sound these headphones provide

The sound is great across the board for an in ear headset, and the bass is excellent

They don't hurt my ears, easy to adjust so that they don't fall off, amazing sound quality with use of the Jaybird app and excellent bass quality

Fit - terrible, spent an hour trying out all possible combinations of fins, nothing worked as it should.2

It is not difficult but, it limits me as I use my headset both home and away