Btw, I
Thanks for the info. If I understand what you are saying, if I have nos px25, getting rd27as might not be priority.
as for my ad1 vs ad1n, I was asking if you have compared a real ad1 from someone like valvo or maybe tungsram vs ad1n. Sorry if I wasn’t clear
No I am saying I don't know because I haven't run RDs under ideal conditions. I am even running Osram PX25 0.7V under voltage, and AD1n 0.5V over voltage. This sort of thing will be happening in all Lampis. It's only because I have been getting anal about what is going on because I am too curious. Most people shouldn't really worry too much, and just plug tubes in and see what works well.
That said, given PX25 and RDs are currently both under run until I adjust my DAC, both by quite a bit, I am still expecting to prefer PX25. But I dunno what will happen until I try.
I have EML AD1 and NOS Loewe AD1, a real AD1. The Loewe are really good.
My favourite Lampi valves are Loewe AD1, Osram PX25 and AD1n at the moment. They are all different in really good ways. Osram is killer for sounding really natural and realistic, really good with acoustic material especially. AD1n the most awesome bass and very good performance elsewhere. Loewe AD1 has a subtle smooth feel to it without adding sheen and just sounds really silky and 'nice'.
I feel guilty using the PX25s and Loewe due to the rarity. AD1n is really the best option as it's relatively cheap and robust enough to handle with less care than the other two. It also has the lowest microphony of anything I have come across. For those reasons AD1n is winner as an every day valve.