How much hum is normal from a new tube amp


I just bought a great sounding Lab12 Suara KT120 tube amp. The issue I am having is a hum that is coming from the transformers. I can hear it with no music playing faintly from my listening position 12 ft. away. The question is, should I return it, or is this normal acceptable. 

128x128blue-magoo

I have the integre4 mkI. No hum. Also, unlike the Qualiton A75 it replaces, it does not exhibit sensitivity to emi/rfi in my setup. The Qualiton did. 

I returned the amp, but I miss it. I had a really good sound. I now have a Luxman MQ- 88uC. Sounds really good as well. No noise.