Hum with PS Audio UO/ Help

Has anyone experienced problems with hum when using a PS Audio Ultimate Outlet? I have a HC UO feeding my Manley mono's and I experience unacceptable amounts of hum when using phono. Less with CD, but still much more than going straight into the same wall outlet.

Any thoughts?

had hum with uo's and my 200w tube mono's, not to mention the sound became slightly 'whitewashed'. Got rid of them and went to none transformer based solutions like sound applications. Got rid of my powerplant p600 too. never looked back since. going to try isoclean next.
I have two P500 units. I am using every outlet on these units including the UO outlets. No hum. Never. I am totally happy.

I do not know what could be wrong for you or the person with the problem with the P600, but you may find contacting PS Audio for advice may help if you haven't already done so.