Quote:
The supplied mains connector is terminated at one end by a two-pin plug. When the Quad 405 is used with a Quad 33 control unit, which should itself be earthed, the 405 will be earthed via the audio lead and should not be connected to the earth lead in the mains cable. In other cases, where the 405 must be earther directly, a three-core mains lead should be used.
So the 33 needs all 3 wires for the mains being connected, but if you're using the 405 with a 33 you only need wire up the Live and Neutral of the kettle plug for the 405 to the mains. Only if you're using the 405 with a different pre- do you need to fully wire the kettle plug earth to the mains.