DC meter on power amp

Have you tried turning the tube that reads higher, down to match the other?           Given my unfamiliarity with your amp, and why those pots wouldn’t affect the B+; I’m hesitant to offer further advise.                                                                                                        Perhaps another AudiogoN denizen, can fill in for my ignorance.                                  Personally: I’d run that 300B pair, that read more closely matched, so as to enjoy the amp, until getting gaining further knowledge.                                                                               My suggestion would be: contact Soundgate for directions and information.                       My apologies, for not being able to offer better assistance.

@rodman99999 
No problem, thank you very much for your input.  

Here's hoping your solutions come quickly!

Turn the amps on and turn the volume to ZERO. Wait 10-15 minutes.

Turn the pot that has a HIGHER reading counter clock wise very slowly until it matches the LOWER reading.. BE VERY, accurate..

LOWER is better, HIGHER and HUMMING is NOT..

Contact the manufacture and ask what the bias range is on the pots and recommended setting for your amp and valves.

Normally lower bias setting =  a lot longer valve life. Changes the way they sound when they are cranked up too. 8W. Needs to be right..

Enjoy

those pots on top of the 300B doesn’t change the readings, no matter where the volume is.  
But interestingly, I just try change the 5AR4 on the high reading side, now the readings match, both about 72mA.  I tried switch the left and right of the 5AR4 earlier and the readings doesn’t follow the tube, so I thought the 5AR4 doesn’t matter.  But it seems it has an effect on it.