Works like a charm:
Spotifree – Free OS X App For Muting Spotify Ads
Make a diff!
After plugging out the headphones again, Mavericks decided to rather do without audio output for the rest of its runtime. As none of the usual approaches worked to convince it to obey and I wasn’t quite willing to reboot it, I did a web search and found the following hint:
sudo kextunload /System/Library/Extensions/AppleHDA.kext sudo kextload /System/Library/Extensions/AppleHDA.kext
I can hereby confirm that this worked in my case (with a 15″ MacBook Pro Retina 2014 model), Mavericks finally obeyed.
via Losing Audio in OS X Mavericks? Here’s what you can do about it! | iMore.