The 8008st uses a single "dual wound" transformer for the power supply where as the 4004 mk II uses seperate transformers(dual mono design). The 8008 series also uses a DC servo circuit for flat operation down to 5 hz. I agree with you i like the 4004 mk II very much.
Aragon 4004II vs 8008st
I just recieved a 4004II and love it. Ive owned 4 krells ksa series and like the 4004II very well. Whats diffrent about the 8008? Better power supply/ heat dissipation/higher bias class A maybe?