I have the M4 Triode Masters and they are easily the most enjoyable speakers I have had in 45 years of having great audio gear. I guess all I can say it that I am an utter and total OB speaker devotee. They music flows effortlessly from the speakers, they are dynamic and quick, and have a wonderfully large soundstage. The are quite easy to drive. Yeah, I love OB speakers for lots of reasons. I have yet to hear the Pure Audio Project speakers personally, but friends that have heard them speak very favorably about them.