Said 'scope contains reed relays, these burn more power than a transistor but still not that much.
If the preceeding side of the relay contact/transistor is decoupled with a cap there shouldnt be a pop, dc is the worst offender for causing that.
I'm not a valve expert however grid leak biasing isnt great, you'll get less voltage swing, cathode biasing would be a better approach in my opinion, voltage swing at the o/p depends on lots of other factors, and I spose the schematic is classified.
Sounds like an interesting project.