So far the 10Y has been my favourite line stage tube. But I often get inquiries for line stages using the 300B. With the availability of the Elrog ER300B and it's superior resolution, this might have become feasible. So I am going to test it with a prototype.
Tribute has wound some suitable OPTVCs for this project. These are some massive beasts the size of power amp output transformers.
Just waiting for some chassis material to arrive before the assembly of the line stage starts. I will report about the results. Stay tuned!