Apple MagSafe Power Adapter causes USB audio issues

Finally found a solution to my problem, so I thought I'd post it here...

I was getting static / hiss / noise / pops / whatever through my external speakers (Yamaha monitors) when my new MacBook Pro 13" 2013 was connected via USB to my M-Audio Fast Track C600. I had a similar issue with my Macbook Air 13" 2012, but it got worse with my new MacBook Pro.

At first I blammed the M-Audio FastTrack C600. I have a little home studio, so I tried unplugging my synths and other audio equipment. It was only when I disconnected the USB cord that connects my Macbook Pro to the C600 that thte noise stopped.

Next I blammed Mavericks and USB 3.0. Apparently some people with Fusion hard disks were having USB audio issues. But my MacBook Pro doesn't have a Fusion drive. Others were blamming USB 2.0 equipment being plugged in to USB 3.0 ports.

I noticed the sound got worse when I used my Bluetooth mouse. I turned off Bluetooth - no luck.

I noticed the sound got worse when I was downloading something, so I turned off Wi-Fi - no luck.

Maybe my old 30" Apple Cinema Display was the problem? No.

I plugged in my Traktor Kontrol S2 to my Macbook Pro via USB and got the same problem. So the issue was definitely with my MacBook Pro.

I got ****** off and unplugged everything. As soon as I unplugged my old Apple MagSafe Power Adapter (I was using the Magsafe-Magsafe2 adapter dongle thingy), the noise stopped.

So I swapped MagSafe Power Adapters and the hissing is gone.

Weird. Hope this helps.