@analogj , Yes, there is also Class G. It's been around for a long time but not so popular. I had a Creek that ran the first twenty watts in Class A then moved over to switching--a Class G design. It was super strong and I loved it.
I've had two Class D amps. Both sound super clear and had gobs of power. The body of the music was a bit thin though. The technology has surely changed. I'm excited to try this one from Marantz. And I'm a tube head!