Ah and thanks as well to Zeke - that answers my question about whether the blue wire could switch two separate units or not... I guess it can!

Oh one thing though - does the Empeg go into sleep mode when u turn the engine off or when u pull the key out? I suppose that depends on the nature of the Switched Accesory line in my car but does anyone know if this varies from make to make or not? I'll have to get my multimeter out and check