Need help choosing replacement tubes for my 211 SET


I have a Voxativ 211 Integrated Amp.  It came with Psvane tubes and they are beginning to wear out, or at least I believe they are since the highs are starting to sound poor.  A few questions, do I replace all the tubes including the driver and input stages?  Is that standard practice?  Finally, what are some good recommendations on replacement tubes for the best sound?  Budget is around $500 but can be stretched somewhat for something significantly better.
128x128mmporsche
Before you invest in changing out the 211 tubes, swap out the 6SN7 driver tubes first as they have a significant impact on the sound of the amp
Not sure the tubes are the problem. Sit tight and see what else might be the problem. Tubes generally last a very long time.

@testpilot Old post, but it is worth a shot: My preamp has a bundle of 6SN7 Electro Harmonix and someone recommended Sylvania 6SN7 as a replacement. Do you have an opinion?