Yeah, I noticed the issue within the first week, but this was after I already transferred over my files and settings.
Though, I'm sure the issue was there as soon I first turned the machine on, I just may have not noticed it initially.
So, since I already went through the process of getting my computer optimized with settings, etc. It will become a major inconvenience for me, as my work hours overlap with the Apple store hours. I wish they did house calls during the evening or weekend... So they can just swap my hard drive to a new iMac that won't have these audio popping issues.
Des, it is a serious issue. Apple hasn't chimed in yet to address the issue... and I feel it would be the right thing to do. Apple should also pinpoint the problem, so I won't have to go through 4 machines, to finally get a working model, like obi can attest to.
What we do know is that this problem seems to only be affecting the 27inch model with the fusion drive.