How do you add a headphone socket to the speaker wires so that the speakers disconnect when the headphones are plugged in?

== Each speaker is driven by a pair of wires coming from the amplifier. One wire is "live" and the other wire is "ground". There are two little contacts in the headphone socket which connect the amplifier's live outputs to the headphones when the headphone jack is inserted. When the headphone jack is removed the contacts reconnect the outputs to the speakers. So it's important to connect the "live" side of each of the speaker lines to these switches - not the "ground" wires which should stay connected to the speakers! Because headphones usually have a much higher impedance than speakers the headphones will draw a lot less power from the amplifier but that won't do it any harm so there is no need to add any extra resistors in the leads. == Connect it to one side of the speaker line. You'd better have a resistor in the lead going to the earphone.