..Mag to answer your question the 601s replaced a pr of 501s several yrs back and it was a major upgrade. I’ve heard some of the YouTube audio “pundits” actually refer to all things MAC as mid-fi which leads me to believe they’ve never spent much time with the 601s. I won’t get into the typical audio speak word salad but will say there’s plenty of resolution without fatigue and bass slam in there in spades…a very taught bass. The Ultra 7s have a lot to do with this level of sonics having won many ‘best of show’ awards. Regarding the MAC/VSA combination, Albert always said there was a distinct synergy with the pairing and as usual he was correct. After putzing around in this hobby for some 55 yrs I’ve pretty much gotten off the upgrade carousel. Thanks for your interest Mag..