sound while on standby?

[Colossal]

The resistor across the switch is great because you avoid inrush current. You can increase the value of the resistor to lower the amount of sound you are getting on standby. Try 220k.

[Ian444]

I've been working on an old amp that uses a 390 ohm resistor for some sort of soft start, but also leaves the screen voltage on the output tubes disconnected until you go from standby to run. Seems to work well. Quite clever I thought.