I've been the proud owner of the 500-S model. Obtained it from the original owner in 1974! He was our church youth group leader and he gave it to me as a gift because he saw that I was a budding "audiophile" and he had replaced it with a modern Sansui receiver. John Shoaf, was his name. Unfortunately, I've lost contact with him, but it was a great gesture, and over the years, it was dragged to college, then stored for almost 2 decades, and finally, I restored it back in 2007. Now it plays in my study. Sweet sound from the 7189's and the cool look of the brass faceplate still gives me warm fuzzies. Still trying to score an MPX decoder, but I just can't stomach the $$$$ those things go for on the auction sites. Anyway, it's a classic, and I love listening to it on my Tannoys. Aswesome sound.