What is the opinion of Reddit about the
Audio Technica AT-PHA10 Portable Headphone Amplifier?

Nyet. That sort of music boosting requires fundamental access to the audio engine.

Ever thought about carrying an external amp?

http://www.amazon.com/Technica-AT-PHA10-Portable-Headphone-Amplifier/dp/B002T6NZMS/ref=pd_sim_23_1?ie=UTF8&dpID=31XjLwahGDL&dpSrc=sims&preST=_AC_UL160_SR120%2C160_&refRID=089AX2NBRQS74PHHD9QG