Bob - I looked at two latest Stereophile reviews of tube amps and I don't see "u" shaped curve.
First: http://stereophile.com/solidpoweramps/moscode_402au_power_amplifier/index4.html
Second: http://stereophile.com/tubepoweramps/hyperion_ht-88_monoblock_power_amplifier/index4.html
In case of the second (Hyperion) it is straight line with lowest distortion at min power. That would imply that u shaped characteristic of SS distortions is caused most likely by nonlinearities (possibly output transistors) around zero. What do you think?
First: http://stereophile.com/solidpoweramps/moscode_402au_power_amplifier/index4.html
Second: http://stereophile.com/tubepoweramps/hyperion_ht-88_monoblock_power_amplifier/index4.html
In case of the second (Hyperion) it is straight line with lowest distortion at min power. That would imply that u shaped characteristic of SS distortions is caused most likely by nonlinearities (possibly output transistors) around zero. What do you think?