MacBook Pro 2011 Distorting Audio Playback
I have a late 2011 MacBook Pro 13" running OS X 10.7.5 which distorts all audio playback. This problem has always been present, however it has become worse in the last few weeks.
I've tried the following methods of audio playback - internal speakers, headphones and external speakers via headphone jack, and even audio over WiFi using Airplay/Airfoil - all of which have exhibited the same distorted audio.
It seems particularly important to note that Airplay was still affected, as I originally assumed the problem was either the physical headphone output or the internal sound card, both of which Airplay should bypass, right?
I tried resetting the NVRAM which didn't change anything.
Has anyone got any other ideas?
MacBook Pro, Mac OS X (10.7.5)