With Silent/Vibrate profile, my battery lasted for five days idle with some voice calls, and at the end it still had 25% juice left. I find this amazing given that with the General profile it lasts only a couple days.

Without any actual proof other than the above, I suspect the unfinished beast that is PulseAudio. It has caused problems on desktop Linux before, by keeping audio devices opened and active even when not playing anything.

I had the power37 kernel with the ulv settings for 125-1000Mhz.