I was reading the Gar book on amps and was reminded about the speaker protection resistor in my Traynor amp. It’s basically a 200 ohm, 20 watt resistor wired on the speaker output jack. One end is connected to the tip, the other to ground. In other words, a 200 ohm, 20 watt resistor from tip to ground.
This can help protect your amp if you forget to plug in the speaker at either end (amp or cab) and can help protect your output transformer. I should put this on some of my amps.