Track's pretty cool dude. If you're not making any money / releasing it - whatever. Worst case scenario: they tell you to take it down or face litigation. The way to go is to find out who owns the rights to the song and contact them before any kind of release. They may want to hear it, they may want...

For some reason the pan knobs on my soundcard don make a difference otherwise I would do that. I think he means in your DAW. I have a similar issue with one of my synths. I just pan the mixer channel that it's on to 90 degrees and the L/R signals are balanced. I've been meaning to solve the problem...

I hear a noticeable difference too, especially on a solo synth sound (i.e. not in a mix).

Somewhere I read somebody say that it had a lot to do with discrete (digital, 101011001) vs. continuous (analog) information being produced.

It sounded reasonable to me, although I doubt that's the whole story.

I use these ones:

http://www.etymotic.com/ephp/er20.html

They work well and aren't that noticeable to others in a club environment. They also don't muffle the sound, but just turn down the volume.

Not sure about their shipping policy.