I have the original 2A3 that came with the Souga. They are Kondo branded. Not sure who makes them.Its difficult to beat a 2a3 except by the likes of 45, 46, etc, provided your speakers can be driven by such flea watts
Which 2a3 tubes are you using
What do you suggest for replacements? It’s not easy to find 4 matched NOS 2A3s at a reasonable price.