With my Ayon Spirit 2 I prefer the sound Gold Lions or Psvane KT88s to either the clear or blue bottle JJs , but you need to try tubes for yourself to see what sound flavor you like.That amp takes 4 12Au7s , I use two NOS RCA 12Au7s blackplates, and 2 RFT ECC82s.
I have 2 other integrated amps that use 12X7s, in my Line Magnetic I use NOS Tungsol 5751s to reduce the gain a little; in my Finale Audio I use NOS GE 12ax7s
To my ears changing out the respective JJ , Electronic Harmonix or Chinese signal tubes that came with each amp took the sound to another level; worth the expense
I have 2 other integrated amps that use 12X7s, in my Line Magnetic I use NOS Tungsol 5751s to reduce the gain a little; in my Finale Audio I use NOS GE 12ax7s
To my ears changing out the respective JJ , Electronic Harmonix or Chinese signal tubes that came with each amp took the sound to another level; worth the expense