How to protect valve heaters from inrush during cold starts?
In order to limit the rushing current in the cold heaters + the current in the empty capacitors, use a 33 ohms inrush current limiter like a negative thermistor (NTC) just made for that purpose in the primary circuit of your power supply transformer. Here is an interesting article about that.

When it’s cold (at start) the NTC presents maximum impedance to the rushing current. After few seconds, the NTC heats up and its impedance lowers down to a ohm or so.