How much hum is normal from a new tube amp

That sounds like a fabrication defect. I would ask to exchange it for another one if you really enjoy the sound. 

@larryi @femoore12 @facten @auroravengeance  and everyone that has chimed in

Yes, I think replacing it is the best idea. It has a great sound, I would keep it if the hum was minor but I feel like this is beyond that.

This is the right thing to do, particularly if the manufacturer is not giving you grief.  You should not have to live with loud noise and doubts about your gear.

Good luck.

The whole system was fine. Only thing changed was the amp which HUMS.

Bad luck, Safest: RETURN IT, for refund, if it's a bad design the next one will hum.

If they can convince you they can fix it, or a replacement will not hum, you have to decide, make them pay for return shipping if you can.

good luck.

I had a slight hum from my speakers (not transformers) when running a LM805ia SET amp that was effectively eliminated using an Equi=Core balanced transformer. The amp has hum pots so some hum is expected. However, with proper management it can be reduced to nearly null.