Help, HUM from California Audio Labs Icon MK2

I replace my Proceed CDP that gave a wrong digital signal to ADC with Cal Audio Labs Icon MK2 (HDCD). It sounds rather dark but okay. Imaging is great. But I am bothered by the hum it makes. I have never had such hum sound with Proceed. What's wrong with this Icon MKII? Is this from the background noise, or low frequency audible from the power line? I really wonder if I can reduce this hum substantially. Please give me some inspiration. Thanks.
Ist thing to try, float the ground, in other words, reduce the 3 prong plug with a 2 prong adapter, works a lot of the time. Then while playing(hard to do I know) move the unit around and see if the hum diminishes. If it does, it a shielding problem. a lot a DAC's can cause interference,in my case my VCR does. Good luck
I have an Icon and have never had hum problems with it

check your grounds and connections