The only reason you get any harmonics is if you drive them to nonlinear distortion though. If you have enough headroom, you can get near-zero transistor distor

The only reason you get any harmonics is if you drive them to nonlinear distortion though. If you have enough headroom, you can get near-zero transistor distortion and then apply your tube modelling digitally. Audiophiles are often stuck in the 1970's with this stuff.