I used my Bose L1 Modell's to for five years and I haven't had any problem at all.
But it has been one month that I checked a muffled sound when I turn on the PA. It lasts for a few minutes and come back to a normal sound after. everything I play or I sing is muffeled and it's getting worse and remains a bit longer everytime.
I'm afraid by loosing my PA during a gig. So is there anything I can do?