Usually, switches like these connect speakers in parallel when connected. So each speaker is connected across the amplifier when it is switched on. The protection device probably senses current, and when current goes beyond a certain level, it trips.For switch connection of two speakers using a switch, I'd use this kind of make-or-break connection to place them across the amplifier. If you hear the amplifier clipping, limit current using the volume control. I don't anticipate any problems doing this.