There was a lot of "In press" discussion on these two. I really don't think in absolute terms the 8008 series is "Better" than the older 4004 mkII. Both amps are similiarly constructed and it is in the highs where the 8008 is said to differ. Some reviewers thought it wasn't as good, others as good. I always liked the 4004 mkII with Vandersteens but never thought it sounded as good as the similiar McCormack amps (especially the DNA .5)
The 4004 series has some age on them now. It would probably be a close call between them at this point even though I never warmed up to the 8008.
The 4004 series has some age on them now. It would probably be a close call between them at this point even though I never warmed up to the 8008.