I'm experiencing an issue with my MBP and am about to call support, but thought I'd post here first. In short, I'm noticing that lower frequencies / bass are not really coming out on the left. Almost makes it appear like the balance is off. A couple of things I've already checked out and know. This is not the issue where people are complaining and it's due to where the "sub" is mounted. I experience the same thing in headphones, not just external built-in speakers. Looking in System Preferences - Audio, it is balanced. Looking in Audio Midi setup it is balanced. I can hear the issue very clearly (headphones or built-in speakers) when sliding the balance all the way left or right. Going right, you get the bass. Going left, it's like a crossover that is filtering it.