I have had the GAN 400 and Nova 500 within my system. As well as others I don’t recal the model numbers. I believe they are low feedback not zero. Just remember this advice is coming from someone who believes Nelson Pass, Dave Hafler, Ralph Karsten, Frank Van Alstine, Keith Johnson, Bob Carver, Dieter Burmester, John Curl, David Berning, Saul Marantz and others should be siliconing and wire tying their amps together. And none really have a clue how to make a great amp. And all could learn a lot from him. So you should take what he says with a grain of salt. On top of that… He’s never had a product brought to market. If he had and had implemented his design features of Wood, Silicone and wire ties to hold his amps together. He’d be a world class Audio Engineer. Or at the very least making millions updating and modifying Pass Labs XA250.8’s. As they aren’t glued together and held together with wire ties. And the people that can afford a cobbled together subpar Pass XA250.8 would be on waiting lists for him to tweak their amps. For me I’ll stick with Nelson, Saul, Ralph for professionally designed and built equipment. I’ll put money on that he can’t make an Atma-Sphere amp sound better. He should buy a set. Tweak them. And Ill bring mine for and AB test to his house, apartment, or trailer park that he lives in. I’d like to see him put his money where his mouth is.