Loud Humming Noise

[markb]

I attempted to build this a couple of years ago but I ran into a problem. There is a loud humming noise. I got frustrated with this so I shelved it.

I decided to give it another go. I just installed the new beta software but I'm still getting the same loud humming noise. It seems to be coming from the left channel by the volume control. I double checked my solder joints and everything seems ok.

I'm not sure where else to look.