Klipsch Image X10 - faulty?

First of all I would like to say thanks for the the review (and the discount). I received fast delivery, received today and they are great .

However I have a problem - I plugged them into my iPod Touch 1st Gen and got sound through both headphones but the left one is a lot quieter. I referred to the manual and the 3.5mm jack is fully inserted. I decided to try the headphones in my MacBook Pro and amplifier and they worked perfectly. Great, balanced sound in both ears. I thought then that the problem lied with the iPod - I tried another two other pairs of headphones (Sennheiser and Apple standard) in the iPod and they worked with balanced sound. Do you think this is a fault with the iPod or the headphones?

Thanks, Lee