@bigtwin , how about your own speakers? They might go down pretty low in impedance, right? And this is a Curl design - so I am guessing it is a no-nonsense design and probably does what it says. I remember from quite some years ago when an online magazine performed measurements on the now discontinued Parasound A21 and found that it was stable even below 2 ohms, when the manufacturer claims only 4 ohms.I believe it was some "power cube" measurement - I could not locate the article for posting here.
BTW, John Curl received an Award at the Los Angeles and Orange County Audio Society this week.