I think you have a point here.I think it has previously been said umpzillion times that even a 12AX7 design (µ = 100 per triode) is marginal by today's standards. So, why tinker with low µ pre WWII tubes and a DHT 😵 close to the beginning of a signal chain? I think it's much better to leave REN904's and especially the scarce and expensive AD1's to radio restorers.
Best regards!