I wondered if there is any advice about not switching off the standby while Pittbulls are in Enhanced mode (with the solid state rectifier operating). When I did this, the amp blew the main fuse. I had just changed the rectifier tube, but since the amp was switched to enhanced mode prior to startup, I didn't think that the rectifier tube swap would be the cause. I could put back the old rectifier tube, and start it in normal mode to see what happens, but I'd rather not blow fuses needlessly. Perhaps starting in enhanced mode puts more stress on the components since the tubes are "booting up" to full idle much quicker than if the tube rectifier is used. This is just a theory, but perhaps some of you might know the answer to this.