Someone pay this man!
Yes, apparently having several hobbies isn't enough, lol. I'm debating working at Panera... Overworked for near-minimum wage, but you get 40 hours a week, social interaction, 1/2 price food, and at least some activity. Blue collar seems all I can get at the moment.
On another note, I'm borrowing a friend's mandolin, see if I can't learn to play a bit
IOOI,
Your username makes me me think of Isos from TRON.
Based of how things are priced relative to eachother in the US, I would say in that price range you have the FiiO E9, E17, and tube amps well-reviewed on Head-Fi yet sold through EBay, like the Little Dot i+ and a desktop tube amp by Fred_Fred_2004. Note that I haven't personally heard any of these, but read quite a bit about them. A more powerful amp ought to make a noticeable difference in the dynamics, sustained bass note authority, "tighten" up the bass, soundstage, "lift the veil," and in general help a headphone sound a tad more refined.
I'm picking a tube hybrid amp for myself, because tube amps add a rich coloration, make the presentation more "liquid," and might roll off the highs just a tad to make them less harsh while no less detailed. The other benefit is how each tube has a unique signature - for 10-20$ each, you can change them like a lightbulb (almost) and experiment with a sound tailored for specific headphones or genres. It's a bit more broad in effect than an equalizer... But equalizers can get you most of the way. I can't yet recommend the amp I bought because it has yet to be finished and delivered, and I think it'll be priced above the range you're looking anyway. With a Solid State amp, you know what you're getting, they're usually pretty transparent so you just hear more what the headphone does by itself.
I would encourage you to look into these models, and pick your favourite
PS Mad, I had hoped to send you the amp before you bought your "end game" tube amp from Audio-GD, but the builder guy only just got all the parts and you ordered your amp pretty quick
Edit: I gave the builder money for his pre-production model a good while back, I just sent him an email that will hopefully light a fire under his seat: have the amp delivered so I can hear it at least 3 days before 30 days are up from the date of payment, or I'm opening a PayPal claim against him. I was being pretty patient, but if he's going to do business, he has to know that people won't wait forever.