sonic frontiers is long gone as a going concern, though chris johnson is still in ontario canada, now running parts connexion, the online hifi components seller, and doing some mods on equipment on a limited basis
you could reach out and ask him his findings on the old s-f line1-3 units
andy and brent are good vendors, their prices on the rare and really good stuff are getting sky high (brent even higher than andy), and their advice is usually valuable on tubes’ sonic signatures, but be sure to be specific about what gear is using their tubes... rolling tubes can make or less of a difference in different gear with different circuits
you could reach out and ask him his findings on the old s-f line1-3 units
andy and brent are good vendors, their prices on the rare and really good stuff are getting sky high (brent even higher than andy), and their advice is usually valuable on tubes’ sonic signatures, but be sure to be specific about what gear is using their tubes... rolling tubes can make or less of a difference in different gear with different circuits