I heard the ART while visiting Synergistic. You can read about my experience here(towards the bottom of the page, paragraph title is WTF?!). In addition, my wife, a non-audiophile, easily heard the difference with ART in vs. out. One of my customers, and engineer who hates, hates tweaks openly admits that the ART works, and it pisses him off because he can't explain why.
Disclosure: I am a Synergistic Research dealer.
Disclosure: I am a Synergistic Research dealer.