Why am I not getting enough bass response?
It's probably because you don't have the right ear seal. Be sure to try out the various ear tip sizes as you may find that you need the double flange design to achieve the best possible seal. You may also want to try pulling the ear tip back slightly as it may have collapsed.

How do I know if I have a good ear seal?
When no music is playing, your voice should sound louder and ambient noise should sound quieter, very similar to wearing a pair of ear plugs. Creating a tighter seal is simple. Insert the ear gel into the ear canal and then gently pull it back. This adjustment eliminates virtually all external noise so you can play your music at a lower volume, for a longer period of time, without experiencing ear fatigue.