Noticed sound imbalance straight away - not impressed
I'm glad I found this thread. I have exactly the issue described. I guess I must be what Calcium calls 'hearing-acute'.

I noticed it as soon as I played some music (Philip Glass) and find it extremely irritating. After playing around with preferences and taking it round to an Mac-owning friend for confirmation, I was resolved to return it to Apple (it's only 2 days old) thinking it was a one-off.
I am not happy I found this fault but happy I found this forum

and thanks for the informed comments on this issue.
I must say I am seriously NOT impressed with Apple on this. This is my first Mac. I find the sound imbalance very noticeable. I want to hear music in proper balanced stereo not skewed off to one side. This is shoddy. It doesn't sound very stereo, quite mono in fact. Why hasn't this issue cropped up in reviews?
My only comfort is that
I am not alone. Also, I don't have to face the prospect of taking it back to the Regent St Apple Store and arguing the toss with them to change it for another one. It would be impossible to demonstrate there because the whole store is so noisy ( I told you I have sensitive ears

)
Is the sound imbalance a deal breaker? (I've only had the MBP for 2 days and Apple say I have 2 weeks to return it for a full refund.) Well it's not just the sound. There's also the matter of the stupidly reflective screen (why don't offer a matt screen with the 13" Pro) and the measly two USB ports together with lack of a pair of headset ports for Skype etc.
There are things I like about the MBP, especially the long battery time and multi-function trackpad. However since I am only occasionally a 'power user' I am contemplating getting my shekels back and getting the Samsung NC20 netbook (£349, smaller and lighter than the 13" Macs, XP Home, 1Gb Ram, 160Gb hard drive, THREE USB ports, 5/6 hours wireless on battery and balanced sound...) I can open the lid easier on the Samsung and won't be paranoid about taking it everywhere with me.