I've had a pair of NS-500s since ~1980. While I've owned lots of speakers (before and since), these remain among my favorites for 2-channel listening, because of their absolutely terrific soundstaging (stunning breadth and depth and pinpoint localization in 3D space), neutral midrange and sweet but extended top end (that beryllium dome tweeter is a MONSTER, in the best sense...weighs more than many midranges! SWEEEEEET, delicate, nuanced, extended, all at once!) I've not heard ANYTHING comparable, given size and driver-configuration similarities.
As mentioned, however, they will pass along flaws in the amplification stage (along with flaws in the source materials and their playback equipment). The low end is a little lacking compared to some modern speakers, although this is merely relative, as the NS-500 presentation, without other A/B reference(s) is compelling across a reasonable bandwidth. They are VERY balanced. That's why I've been unable to part with them for three decades!
If you get a chance to audition a pair in great shape, I think you'll be impressed. Mine, unfortunately, are now relegated to a closet, due to a recent move...but I STILL won't part with them (I won't be living here forever).