Ditto recommendation of Tung Sol 6SN7 reissue. They get pretty close to the good characteristics of NOS Russian 1578.
6SN7 driver tubes
I need to replace a few 6SN7 drivers in my amps. They take 3 per side. I've been using Sylvania 6SN7GTB which sound great, but they're pricey to find reliable ones. I've been considering EH or Chinese brown base. Any thoughts on these? Or any other recommendations? I want to keep the cost under $20 per tube.