Although the Marantz is very smooth, compairing them to the 501's is apples to oranges. Both have a wonderful sound-stage and tons of power but the similarities end there. The Marantz is very detailed and tight in the bass. The 501's are less detailed and have an overall softer sound. If Mac and Krell are at opposite ends of the spectrum, the Marantz Ref is in the center.
Both are wonderful and would provide a satisfying experience in their own way.
