My issue that I just found out today(and yet another issue with the Ultra that I'm unfortunately having) is that when using a turntable plugged into the Ultra's phono input, I had no buzzing/hum. This table doesn't have a grounding issue anyway so need to use the Ultra's grounding plug(which however inserted into the Ultra). However today I used a different turntable, that is using a different phono and that is grounded with that phono. That phono was using the Ultra's Line In. And I got a lot of buzzing/hum. When I attempted to ground using the Ultra's ground, the problem persisted. Only when I removed the Ultra from the system completely did the problem stop and the table was quiet again.
FWIW, the Ultra was sitting on top of the preamp that the second table is connected to.
I'm getting the feeling the Ultra is going to be returned soon.