An Amp Designer said this: [person complaining about an amp not being able to be biased hot enough]...was using a bias king or something similar! These questionable tools are only any use in 50 watt amps that run on two output tubes. The readings on a 100 watt amp will be wrong, causing the amp to be biased well into the danger zone when using one of these tools! I heard that the person in question took his [amp] to a tech to have a resistor changed to enable him to bias the amp hotter. I would love to know if his amp still works? Its a good job that [the amp's] 100 watt transformers have a full half an inch more stack (both mains and output) than pretty much every other 100 watt amp out there (notice the weight of em?) which means its just gonna be tubes and fuses that this person will be buying at a rapid rate! Any merit to this?