I've used NOS Brimar 13D5 and CBS/Hytron 5814A and enjoyed the sound, but they're expensive and were not long lasting. I've found the reissue Tung-Sol 12AU7W/6189 tubes from Cryoset sound good, are affordable, and last a long time.
Tube upgrade for Unison Research unico
The unico will be my first tube amp(coming next week), so I am a tube beginner. Does anyone have experience with a tube upgrade for the unico? What sonic improvements will how much money buy? What tubes should I consider? I listen to everything, but most important is how acoustic instruments sound, high resolution, their smoothness, their attack, their harmonic richness & warmth.