None of them were.
Infinity made the claim, not me. Oh, I guess I did...but I was referring to the Infinity's claim. I know they aren't a true labyrinth design but they stuffed the cabinet with absorbent material and lowered the port resonance. Maybe it was just fancy sales writers but they made the claim.
My Infinity Monitor IIa’s are transmission line.
One of my favorites, only to be replaced by my Reference Standard 2.5s which I kept for many years.


