The bass question is interesting as I have been comparing my headphones (out of DX90) in anticipation of writing some sort of review of my new gear - I have a pair of custom W4Rs and I have read in numerous posts that they are bass "light" in comparison to some other choices (I never heard the universal version - I bought on reputation)
Some of the selections I have chosen to compare bass output, texture, timbre, etc... are Rage Against The Machine, Sublime, Yes, Dave Matthews among others. What I have found is the W4R is anything but bass light - they go very low - and get good volume - they aren't JH16's or 1964 V8's, but I can't imagine anyone (even a bass head) not thinking the bass was solid.
Maybe there is a problem with his unit - because this little DAP has a solid low end. SOLID. I don't use an amp - so far all I have listened to is Apple Lossless - and I don't touch the EQ.
Bass light? I don't see (hear) it.