@matrix A preamp on a 500 series is recommended. With the 500 drivers, you should probably also get a DAC. FIIO makes great portable DAC+preamp devices. I used a Q1 on the go until it turned into dust. If you want to skip the DAC, though, you can get some portable preamps that work nice for a solid bargain.
FIIO stuff is meant to work with your phone. Android has USB OtG so you can just plug it in for the DAC or use it with the preamp only.