When doing a Star Ground to a tube amp every stage which has own power take (B2, B3, B4 etc) should have own wire to the PS last capacitor negative terminal. First all stage currents are lead to a Filter capacitor negative where wire continues to the PS. Just like all stage currents can be thought to begin after a voltage dropper resistor which usually connects to same Filter capacitor positive terminal. Only exception is/are power tubes where both Anode and Screen return current uses the same ground wire because currents meet already on tube cathode(s) so B+ = transformer and B1 = Screen has only one ground wire. Usually there is one ohm resistor on each tube cathode where ground begins. There also a thicker wire could be used. I have used one square mm which I think is about AWG18 but current there is quite small so perhaps it means nothing?