[kvdmeulen900]

No issue with your heater current as long as you don't implement DC heaters for the preamp. The "old" RKT 30VA was designed with that in mind. I think it is also used in the small Jim amp.

Since the “old” 30VA was used in the 5W Jim amp, I suppose it’s safe to use for my purposes as the current draw is roughly the same.
I’ll start building the amp and will post the results when it’s done