He's speaking the truth. If you enjoy sleeping in silence then you do not want tinnitus. I already have it and basically you'll never hear dead silence again and you'll damage your higher frequency hearing if you already haven't. Maxing out a Clip I would assume to be at least 95dB, which would pretty much permanently damage your hearing within hours.
If you really want to though then just get an E11. Bass-boost would remedy some of the kick (while boosting the punch aka mid-bass even more), but the HD25-ii's are known to have punch, not rumble/kick. You can't really alter that aspect of a headphone without internal modding and even then, modding only can remedy it or alter it to certain points, often while making other aspects of the headphone sound worse.
If you max the E11 out though, you will either be going deaf (figuratively, but pretty close to deaf) within a few months and won't ever be hearing music again or you'll blow out the HD25-ii's drivers before then.
And don't be anal / ungrateful. People recommend what's good for the long term and what is good for your health. If you don't appreciate that on an audiophile forum (where pretty much the entire population of the forum consists of adults), find another. If you really want to damage your hearing, then go right on ahead, but I wouldn't doubt that you'd regret it. I already do and I'm only 17. I can only hear up to 12kHz rather than ~19.5kHz now, aka I can't hear some frequencies of the crickets chirping nor certain aspects of songs. Sometimes the crickets get blocked out my tinnitus when it's dead silent because it's that loud / attention-grabbing. Mosquito's buzzing sound has been long gone and I liked that so I can find where the hell they are and kill them when they're in my house.
And really, you won't need an amp unless your sole purpose is to drive them to deafening levels (to the point where people around you can hear your music, even though it is a closed headphone. That is beyond deafening). Sound quality won't change at all (unless you have like superhuman hearing, and even then, I doubt there would be much of a change if any).
Here's a dB chart.
http://www.gcaudio.com/resources/howtos/loudness.html
