any gas tube regulator, like 0B2, 0A2 can be used...anyway, only the first stage common cathode need regulation, the second stage cathode follower may do without it, at 200volts supply, this is plenty if you only need 2volts or so output..
tubes like 6DE7, or 6CM7 can also be tried....the 6DE7 operated at 10mA or so will yield even lower output impedance, enough to drive a high impedance headphone....
just don't mention the name "4play" and we will have no problems...