how loud does it go?
at the end of the day it is an opamp that can drive 600ohms minimum. Lots of headphones are 32 ohms, so to get this situation to work you have to throw away level in an output series resistor.
for all the palaver on the listing they don't mention output impedance. Output impedance affects the sound.
but it's cheap ( at the moment ) and could be just the ticket