Sudo killall coreaudiod

Hey guys,

While most of the time I manage to solve my problems using Google, I don't seem to find an effective way to get rid of this one.

I was doing stuff on Chrome, on my MacBook Pro with the latest Yosemite version, and all of a sudden I lost sound. I have an external USB sound card plugged in so I unplugged it and replugged it back but still had nothing. Then I noticed I had no control what so ever on the volume parameters with the F keys, and while in the Sound panel located in the System Preferences, my sound card was detected, I couldn't change the output to internal speakers and select my external sound card as an output back again. So I rebooted the computer and did a PRAM reset. It seemed to work but as soon as I wanted to check if I could change the output parameters it started to funk up again. No control on the volume. SMC reset did nothing great. PRAM reset again : I had the sound from my sound card by selecting it, sometimes from the internal speakers, with no logic at all. Sometimes a "forbidden" sign when I tried to change the volume, sometimes the little white boxes went up and down but the volume stayed unaffected, etc etc. There was no pattern I could rely on to understand where/what the problem was. It just went random every time. I tried to plug/unplug headphones in the computer socket, did nothing. I tried to change Audio MIDI setup, did nothing. I deleted the Audio MIDI plist file in the User Library Preferences, deleted the Audio folder in the default Library Preferences location, replaced it with a new one I created in the Terminal followed by a command to set the permissions right, according to what I found on different forums. Turns out that the only thing that seems to work is typing "sudo killall coreaudiod" in the Terminal, but as soon as I reboot, the problem comes back again. I created a new MacBook user and logged with it. Everything seemed to work flawlessly in this session.

If somebody has a permanent solution it would be great ^^

Sorry for my English and for this long, annoying post...

Thank you,

Jules