I was at an audition and got to use an SWR Workingman 4004 head w/4x10 cabinet. I noticed there was a limiter knob with a green light that kept flashing. I assumed that meant the power amp was clipping so I had to keep turning down the master volume. It didn't help that the other guitarists were going bananas with the rented Marshall stacks. Anyways, my Yorkville amp only has a limiter button which I keep on all the time. How do I use a limiter knob? I've never heard of that before. Since I don't own an amp with such a knob, I can't experiment at home.