Why am I all of a sudden getting hum in my system?

I have had a Manley Chinook phono pre-amp in my system for three months and I am now getting a hum that gets louder as I turn up the volume.I disconnected the Vpi Classic One and I am still getting hum.There is no hum when I connected my Belles phono pre-amp so I am guessing the Chinook is the culprit.I called Manley Labs yesterday but they are closed until January 2.I have tried to solve the problems with suggestions from other threads on this site with no luck.Any help would be appreciated.
In my experience Humming noise comes from two main but not exclusive sources, 1. RF interference (Radio Frequency Interference) - or - 2. A bad or weak ground.

However in your case you're dealing with phono outputs and there can be some impedance matching issues involved. Check your amp input for an alternative phono setting. If that doesn't pan out, you could directly ground the phono to the amp being used. If that solves the problem then you've answered your question.
Hope I helped.

Synesthesia Studios