Has anyone switched from Class AB/A to Class D? Was it better? Was it worse?

It depends, but when someone like Ralph @atmasphere builds a GaN amp it’s a pretty strong indicator it’s a legit technology.  As always, it comes down to personal preferences.  I’ve heard Class A/B amps sound sterile and Class D amps sound utterly musical, so again it depends.  Why are you so against room correction?  I heard Lyngdorf’s RC and it was pretty awesome.  

When the air conditioner in my small house could not keep up with the heat input from my Pass XA30.8, (ok, slight exaggeration), I said to myself this is ridiculous and I don’t care how much I liked the sound. Additionally, moving the 75 lb hulk every time the wife wanted to move furniture was equally ridiculous.

I went to a Hypex based class D amp that weighed 13 lbs but I was not crazy about the edgy sound. Then I went to a Benchmark AHB2 which is class H or something, and never looked back. It is a compact powerhouse.

So in summary, my motivation was more about convenience than sound but it worked out well in the end once I discovered Benchmark. Sometimes I miss the Pass sound but not enough to ever go back.

Amplifier class is just that. A different topology and implementation.

Doesn't correlate with sound quality at all and yes I use Class D.

Remember Class is  moniker for different topology. It is not a grading system

Doesn't correlate with sound quality at all and yes I use Class D.

Agree, much of the time. Since Class D is relatively new and the kinks are still getting worked out, I think there is some correlation to sound quality – but as you point out, not because of the topology, per se.

If someone said to you, "You can can have one free amplifier worth $1000 and we won't tell you which brand or topology it is," what would you choose to ensure the best possible sonic outcome? At $1000, I'd choose Class A/B.