I've had a unibody Macbook for about six months now, and love it - the only problem is that recently I've noticed that the audio is no longer in stereo. At first I thought it might be my headphones, so I tried a set of new iPod headphones, a pair of Sony regular ones, and two sets of external speakers - no luck. Basically, the machine seems to be "blending" the stereo channels. I first noticed it in songs that have guitar in one ear only, for example. I tested it by opening a mp3 in Audacity, stripping out the left channel, and playing it in both VLC and iTunes. In both cases, the channel I kept played fine, but the other one also played the audio, albeit a little softer and with some echo. If I had to describe it, I'd say that it sounded like a set of speakers that are hooked up out of phase. It happened the same on the other headphones and on external speakers. The weirdest part is this: the sound is fine in Windows. I figured that it had to be software, and did an archive+reinstall of Leopard last night. When the computer first started, it was fine (the sound was back to normal). However, I then ran system update overnight (which upgraded to 10.5.7, among other things), and in the morning, the audio was back to echo-y mono. What could this possibly be? I really doubt that it's the software update, else other people would have heard of this problem, too. I don't have any crazy software installed (in fact, i did a complete reformat two weeks ago, so the system is "fresh"). Right now, I have firefox, VLC, skype, thunderbird, transmission, and AppDelete installed - and that's about it. Any ideas as to what my next step should be? Thanks!