I use an external "station speaker" for all rigs. I installed a headphone jack in the speaker cabinet and feed it through a 470 ohm series resistor to make the headphones the same level as the speaker would be. I then put "anti-paralleled" 1N914s (or any other switching diodes) across the headphone jack to limit any surprises. The old landline telephones did this for decades. It works nicely. 73, ND6T