Don't take this bad, but... you're going to hurt your ears and lose hearing, are you aware of it?
This said, look for a high sensitivity phone and feed it with a good source (e.g. Cowon D2). Such a combination, when used to the limit, is guaranteed to cause you permanent hearing damage. It can take some time, though, so you may want to try sitting near an airplane taking off, which may produce sound levels above the pain threshold and can render you deaf quite fast. Also, it is funny to see those monsters taking off

Now, seriously: it's easy to find loud enough IEMs and insanely powered portable players, but be VERY careful with them and with the sound pressure levels or you will be deaf (or suffering with tinnitus) quite soon.