I have a problem with my just-finished beta22. It is a three channel configuration with the sigma22 acting as power supply. I did all the initial checks and everything was fine. I connected a headphone while the amp was off, then switched it on and turned up the volume. Everything seemed to be normal and I could listen to the music. But then I disconnected the headphones while the amp was operating and this seems to have burned both the left and right channel . As far as I can tell, all four MOSFETs of the right channel are blown, as well as Q24 of the left channel. Everything else seems to be fine, at least as far as I can tell from the readings of my multimeter, but I guess some more parts might have been destroyed. My question is if anyone can tell me what caused this. I guess it is because the left and right channel were shortened during disconnecting the headphone, but I read that this is normal for phone jacks. Is the amp not constructed for that or is there something else wrong with my amp? Any help is appreciated.