i've heard that on occasion. i like it. thx for the explanation.Cathode bias also becomes apparent with dramatic input swings. If you aren't playing or are playing a quiet passage and then dig in, the dramatic voltage swing shifts the changing bias too far. This overshooting results in a gritty short lived distortion. The bias then settles back to where it should be. This is a characteristic of cathode biased amps. This is coupled with the sag in the power supply that also causes some grit.
Are you serious?