Thinking of getting an amp, but alas; What do?

[Kayito-san]

If a picture is worth a thousand words...

I mainly listen to metal, some jazz, and I've been meaning to get into classical. In any case, I got my Pro 900s last Monday, and while I've only put on a few hours thus far, I've been informed that the 900s generally perform much better with an amp, and "scale up nicely". In this case, I'm looking for something portable. While I'm not in a particular hurry to pick up an amp, I would like to know what I should look for when it comes time. I don't want to spend more money on an amp than I did on my headphones ($525 CDN) obviously, but I'd actually like to keep my expenditure in or around the $100~150 CDN range. I've considered doing a DIY amp (Mini^3 or such) but I didn't have much luck making a CMoy, so I'm a little unsure about that approach.

Anyways, all input is appreciated; Thank you!

[Sean8]

Get an amp. When I bought my HD555s I didn't have an amp and then I got the fiio e3 for about $10 on ebay. Even a little amp like that one opened them up a lot. Now I'm prepping to buy another amp and build a cmoy for fun. I highly suggest getting an amp.