Jolida JD-100 New unit with bad HUM.....hum

I am in the process of breaking in a Jolida JD-100 C. Johnson’s mod #1. I received the cdp last night and have played on repeat for 15 or so hours. Out of the box listening was a little rough but improving every few hours. I like rock and roll and a bit Loud (so I’m told). I’m very concerned of a distinct hum that I am hearing at moderately high listening levels especially when I pause the cd. I have checked the power on both a house supplies and through a 5kva isolation transformer the I installed for my components. Tried grounding the JD-100 case from the ground terminal provided on the unit but no help. I have changed interconnects still the hum is there. I have change inputs to my pre and still get the hum. The CJ mod has upgraded output (RCA’s) so I tried the original and still the hum. This is the first experience with tubes I have had since the 70’s and I don’t know if it is just the normal tube hum or if I have a defective unit. Anyone’s advice would be greatly appreciated. Thanks T. J.