Left channel louder than right?! Why?!

[ishou]

I have to go soon, but I've been having a problem...mixing down from my 4-track to my computer, I've noticed that the left channel is consistently (and significantly) louder than the right (by about 6 db maybe). What could *possibly* be causing this? I have the pan set to right down the middle, even left and right. The problem is corrected if I pan to the right a little, but this is supposed to make the right channel louder than the left, not even!!! Aargh!

[beetlefan]

Check your soundcard's mixer.