Quad 405 switch-on behaviour
Take a look @ the voltages on the output of a Quad 405 board when it is switched on.
We are talking about 110V Peak-to-peak during 60 mS.
That's why we'd better use a loudspeaker delay like the Velleman K4700.
Dada Electronics will launch a loudspeaker-protection / switch-on delay adapted for the Quad 405 to 909 Current dumping amplifiers in the coming weeks.