Overall I think the HE-500 are a better or more versatile "all rounder" headphone than the HE-6 because of the very high amp demands of the HE-6. They have great speed and detail, good frequency balance, a nice soundstage and imaging, good presence and good transparency. It's what the HD600 "should" have been, and while auditory memory is short I think they remind me a lot of my old Stax SR-404 Limited Edition but with better impact and a more cohesive soundstage and imaging. I'd love to get my hands on another 404LE and compare them someday.
(small clip from from mini review)
Nice review you did Larry with good thoughts on comparisons and reasons for the good marks of the HE-500.
I look forward to what you think of the new output transformers. With the secondaries in silver, most all of the benefits of a tans with total silver are gained. The guy I used to work with out of Las Vegas started doing that with great results.