Have a new Mac Mini, and using new external JBL Speakers. They seem to be 'asleep' most of the time, as I don't hear alerts, and when I begin to play something from a website or iTunes, I have to press the up volume button several times to 'wake' them, then lower to desired level. Once playing, they tend to fade out, and I have to hit the up volume again, then lower. This will happen several times, then they seem to finally stabilize. I really haven't tested the mac w/o speakers to see if it does this via the internal speaker, somehow I suspect that probably works ok, that it's something else.