The THD+N numbers hes stating for his spice models are so low the noisefloor makes it hard to see the distortions.

THe more i read the more i understand.

its great stuff!
now reading how,4ohm loads always distort more :-)
(think of the car audio guys running 0.5ohm loads with quad coil 15"s!)

Also ..how he prefers class A or class B rather than class a/b.
He seems very intimate with his spectrum analyser also! its like his best bud! trusty FFT providing a basis of proof of improvement.

Cheers