Zvox 325 hum

Just reconnect my Zvox after over a year, the Phase Cue control was causing a ground type hum but not when it was reduced. Is it a problem or a "feature" that I was not aware of?

This is about 10 years old.

Thanks.

More like 2007 but felt like it's 10 years old.

On the instruction manual, here is a possible cue:

"If you hear a consistent “hiss” or hum, try
turning UP the volume of your TV or other audio
source, and then set the ZVOX volume level
LOWER. If your TV is connected to a cable box
or satellite receiver, try turning its volume control
UP – so that when you switch from your cable
box to your DVD player, they play at about the
same level. As a rule of thumb, try setting each
device at about 75-90% of its maximum volume
level -- then turn the ZVOX 325’s volume control
up as far as it will go without distorting.
In some circumstances, you will hear excess
hiss if your TV/audio source is turned up TOO
high. If this happens, try adjusting the TV/audio
source sound level DOWN and turn the ZVOX
325 volume UP."

I adjusted my TV volume to zero previously...oh! well.