I have a L4 G4 and I have rolled a bit. My opinion:
- Sylvania 6SN7W Short bottle. My favorite tube, best tonal balanced to my liking.
- Sylvania 6SN7W big bottle. My favorite too, a bit less accurate but bigger soundstage.
- Ken-Rad 6SN7GT VT-231 . My second favorite. Bass to die for.
- 1578 Russian tubes. Comparable to the best. Very recommended by Lampizator. I like them too but I find the timbre a bit strange.
- Tungsol 6SN7WGT tubes. Good overall but not as good as previous.
- Default Sovtek. So so, all previous tubes sound better to my liking. I recommend you to try others.
Then I have tried different rectifiers. RCA came with my Lampi and I prefer the Sylvania 5Y3WGT and Bendix 6106 being the Bendix a bit bass shy but more controlled a the Sylvania a bit more natural sounding.