Bazaar buzz

Even with interconnects from amp plugged into the pre, on or off, plugged into wall outlet or not, I still get a buzz/hum, though it appears to change the sound of the buzz/hum, but not the volume of it. 
I tried different interconnects and some are worse than others. The unshielded one being the worst offenders. 
Tried unplugging all kinds of stuff in the house to see if that would help to no avail. 

Put a 30k Resistor across them and watch it go away. :)

Do you mean across the interconnect rca plugs?  How does one do this?

Sorry misread your first post, as you have a buzz when the inputs are open circuit, but in fact it’s the only time the buzz is not there.
See if you have a buzz when you plug in some "shorting rca plugs" into the amp.

Cheers George