NOS 2A3 or Sophia 300b 2.5v in Consonance Cyber30?

I picked up an Opera Conance Cyber 30 2A3 SET amp to use as a headphone amp. Aside from a very slight hum (that is not noticeable when music is playing) it sounds nice with my Grado GS1000i headphones. I am currently using an RCA ECC83 driver and Sovtek 2A3's in it but would like to try upgrading the power tubes. The two tubes I have been looking at mostly are the RCA double black plate and the Sophia Electric Princess 300b 2.5V. I am new to this so I would welcome any input or suggestions from you experts.
As you have a 2A3 amp for headphones, you should first consider 2A3, Sophia Electric has good sounding2A3 tubes available.

People buy Sophia Electric Princess 300B 2.5V for more power, dynamics when using 2A3 to drive speakers and for 300B sound from a modest 2A3 amplifier.