Try a Safe Mode boot ...
Startup your Mac in Safe Mode
A Safe Mode boot takes a longer than a normal boot so be patient.
Once you are in Safe Mode, click Restart from your Apple () menu.
That deletes some system caches that may help.
If Safe Mode does not help, it may be corrupted audio preferences ...
Open the Finder. From the Finder menu bar click Go > Go to Folder
Type or copy paste the following;
Click Go then move the following .plist files from the Audio folder to the Trash.
Restart your Mac. See if that made a difference ...
message edited by: cs
same issue here - very odd. Sound distorted badly when using airplay, headphones and built in speakers... I tried airplay with my wives computer and then mine and the difference was massive.
I've reset PRAM, run hardware diagnostic and tried Safe mode restart - nothing helping. Is there a "sound card" that could be broken ?
We (my music teaching colleagues and I) are having the same issue with our new 2013 13" MacBook Pro systems. When we connect the computers to our classroom sound systems through the headphone jack we get a horrendous hiss-hum-buzz coming through the speakers. The sound technician has been in countless times, and today he used his PC to connect to the sound systems. Guess what? No horrendous sound issues.
This also has occurred with my personal 2011 MacBook Pro and our previous 2008 15" MacBook Pros.
What is up with the MacBook Pro sound cards? Has anybody taken their system to the Geniuses at the Apple Store?
Musicbud, that doesn't actually sound like the same issue. I'm specifically referring to 'distorted' audio (i.e. the audio sounds overdriven, badly processed).
Sounds like you're experiencing interference on the headphone output due to other USB, FireWire, Thunderbolt or MagSafe connections. Try connecting one of the MacBook Pros to your sound system when it is disconnected from ALL other peripherals and external connections, see if that eliminates the noise. If so, it's probably one particular device or connection (I'm guessing a USB device) which is causing interference or a grounding issue.
If the peripheral is required, I'd look into purchasing a simple, cheap audio interface or digital to analog converter (DAC) to bypass the internal soundcard which is susceptible to interference.
Or I could be completely wrong about all of this, in which case you should repost your problem as a separate discussion where I'd be happy to try and help further =)
Also all this metal macbook pro, Mac Pro mouse, the newer mackie universal control, is doing my hands in and being a musician I need them for my job. I will either completely jel up the whole macbook pro with keyboard cover, body and track cove(which is sprayed with nickel) or get a refund. Leave the metal at the scrap yard don't make people who work with computers touch metal all day ;)