Who knows! I bet no one can tell which is which in a level matched
double blind test though. I like the simplicity of the ATI, but I don't like it's weight, imo they are unnecessarily heavy. Anthem seems to have smaller transformers vs ATI's, though they still advertised them as "oversized" (sounds ridiculous to me, but it works for them
) and less storage capacitance but maximize the output devices for good dynamic output as well as short duration output (3 secs). I like that approach because truly continuous rating is not necessary except for people who listen to compressed music at deafeningly loud spl.
I actually feel a little sorry for people who believe firmly that even good quality amps like Anthem, Bryston, Classe, ATI, NAD, Parasound's would sound so audibly different, and requires proper matching to preamps and loudspeakers. The thing is, how are they ever going to decide on what to buy if that's what they believe. They can't practically try everything, so are they are end up relying on subjective reviews and hearsay?
I rather rely on science, specs, and measurements. People don't get to land on moon, let alone MARs if specs and measurements and not good enough. But then, that's just me, as they say ymmv..