Audion Silver Night 300b 20th Anniversary

I agree with the above that a tube swap may not resolve your issue but if you want to improve detail, even at the low end a mesh tube might work.  Generally, I find mesh plates are more detailed tubes. The issue is, flabby bass is more reflective of the output transformer rather than the tube.  

At a lower price the Sophia Princess 300B Mesh starts at $425 (longer warranty is more) and at a higher price the Emission Labs 300B mesh at $895 are going to be a better tubes that will offer max detail.  

I agree with tim_field. I am not sure that different 300b will fix your issue. But I guess that trying one other version may make sense. My favorite 300b are Takatsuki, but they are very pricy. I also liked Sophia Electric RoyalPrincess.

I have the Silver night special anniversary edition (champagne color) 300b amp and changed the JJ’s to Kron Anniversary 300b’s and I really noticed a nice difference. More authority overall and detail improved. I also had the caps upgraded to V caps so this also bumped it up to another level. I’m driving Zu Soul Superflies which are 101db sensitivity so there’s plenty of power to fill the room. I usually only turn the volume a quart of the way up to hear what makes me happy. 

Thank you for the reply.  Which version did you own?

I had Audion mono's a while ago, whilst the very coloured midrange is great for vocals and guitar it is a bit "one trick". The bass wasn't very good. I sold mine on. I'm not sure changing your valves will fix this.