First one of the list...what should we muse about???
Ok lets go small triodes. The king and queens of small triodes are the c3g , 437a , D3a and the EC8020. These are high transconductance tubes and are specced for high end equipment back in their day which means they have top specs and can be expected to last for longer than any other tubes
C3g - siemens telefunken lorentz valvo. Telefunken sounds the best followed by valvo. There is the C3gS variety that we know of and tat is of a high performance spec wise. Siemens have the C3Gs on their boxes but not on the tubes whereas Telefunken and Lorenz have the C3GS on the tube body itself. This tube has a grounding pin and that can be used well to decrease noise even further. This is a precise tube good details and soundstage
437a - a western electric tube. earliest have square getters on top , later ones round getters. There is a variety with a pip top as well - thats rare rare. This is a warm tube as can be expected of WE and quite an alluring sound. Match it with a tube with higher resolution and it will work very synergistically
D3a - ahhhhhh this is a good one folks. siemens, philips, swedish,telefunken,valvo. gold pins. The one to get here is the pinched waist. The straight waist sounds not too good to be honest. So if you have to get get the pinched waist. I am using 4 of these atm in my dac as 2 pairs of double triodes and they are simply.....the best hands down. get the valvo if you can
EC8020 - the pricey one. ebay prices are crazy for this one. I learnt of this a few yrs ago from Thomas Meyer reading his blog of the EC8020 he uses in his phono stage ( one thats hopefully arriving for me soon) . These tubes i have used in a dac. It is a powerful sound, upfront honest but lacks a bit of warmth. balance it up with warm cables or other warm sounding tubes and that should work well . Is it worth it? I think i am the only guy on this planet to ever plug them into a dac. These are low noise low microphonics hence that is why Thomas uses it i his top phonostage. They are i understand more optimised for small signal currents like mc rather than that in a dac signal; i had no issues with its use though.
Hope useful....more musings to come