The sony is an sacd player so I think you would have to say that it is the red book play that is thrown in for free. When I bought my player I wanted something that was top notch on sacd and at least very good on red book. The sony has more than fit the bill. The red book sound took a while to break in, I would say at least 100 hours and I guess the best words for its sound are laid back and very smooth, very detailed like the 508.24 is but not sounding the same at all. I think if I had the 508.24 I would like it better on some music and not as good on other. When I bought mine I almost bought the 508.24 and had a hard time with it but I wanted an sacd player so I bought the sony. I think the 508 is a little better threw the mids but not as good at the very bottom, at least on my system. Its not really fair to judge it on sacd with any red book player on the market because none of them will play sacds. I will say that all sacds are not recorded with the same care and quality just like every format but when you get one that is your system goes to a whole nother plane that red book can not compete with, IMHO.