I found that my Audioengine A5s (which I received last Tuesday, I think) have a brittle stuttering hum whenever they're powered on. Part of it is that I have pretty good hearing. I was just a few moments ago listening to a podcast through some Alessandro 1s (whatever the cheapest model is) in a silent room and I could make out the hum. It was very annoying. I switched on some music (a Tortoise album) and when the music is louder, I can't really make out the hum. But when the music is quiet (drum fills and you know--it's Tortoise, it's always kind of quiet [dynamic might be the best word]) I can definitely make out the hum. I have them plugged into an extension cord that's plugged into a power strip with a million other things plugged into it (other extension cords, a lamp, a guitar amp, a computer, the router, the modem, maybe some other stuff?), but that is my only option. I'm not really sure what to do about it. I emailed support, and they gave me back several things to test (move them to another room, try a different source, etc.), which I have not had time to do yet. I'm at a loss. The speakers sound amazing, but this clipped, brittle hum is driving my crazy.