Originaly built three years ago for my new RE0s to get rid of hiss and get some more bass from FUZE2 and I've hit the target accurately. Anyway, after some amount of time, I found it to be easier and more reasonable to just simply set up the EQ in Rockbox. Now using Comply T-400 it's quite enough.
By now using in combo with uDAC2 and ATH-M50S when playing music from foobar (using kernel stream, resampled) or watching movies (direct sound). That means, it's always supplied from 15V linear PSU, so battery works as a filter, together offering a bit lower impedance at the output aswell. That's actually only good for ATs. Bass is very extended, but not excessive or annoying. Rather well controlled? Cannot really talk about highs, here seems to be influent the supplying method of the DAC (usb hub with pulse PSU), but sharpness and plenty of details that are about to be revealed are present.