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.
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.