Has anyone ever heard of a product or what happened to the ACE concept?
Papers were presented to AES, but I have never seen any product. Did servo take over instead?

If this is the same thing, KEF incorporated it in some of their products. I think it might be their technology.

http://www2.kef.com/us/technology/ace

Totally different. This was a method of applying negative impedance at the amp terminals.
Published by Karl Stahl in 1978. Vol II of the AES anthology, page 241 if you happen to have one. He claimed very low distortion.

Looking at the Kef Video, it looks like they have discovered carpet pad.

Looking at the Kef Video, it looks like they have discovered carpet pad.Carpet pad?

No, dude, it's a way to keep your speaker smelling fresh.