Are there any class a/b amps in your opinion that have gotten it right? Thanks
Zero feedback is one way to get it 'right'. The problem is its very difficult to get the Gain Bandwidth Product needed to support both the gain of the amp and the amount of feedback used and also have the amp be stable; the goal being that distortion does not rise as frequency goes up.
Zero feedback is one way to get around that problem. On top of that though, there is always distortion. IME its important to be pragmatic about that fact so a savvy designer will see to it that as best as possible, the primary distortion is the lower ordered harmonics.
That's a bit of a trick! The topology of the design has enormous influence on the kind of distortion created.
I think there are some solid state AB amps using feedback that meet this criteria. Ayre makes a zero feedback amp that has gotten good comments and Pass Labs has done well too. I think there are others, but not many of them, maybe five or six! I've not done any kind of study in this regard.