I tested 560s, 660s2 : both are a sit back experience. 560s a little dark and 660s2 more bright with a lack of bass. I am now in the grado sr325x. I tested also the rs2x and it is like the grado with the big bowls, but sit back or silk sound. Thing is I like grado sr325x because you can tune the sound with the foams and is more a “you are with the band” experiencie.

Asking for the 600 is mainly because I looking for a silk sound but 660s2 at 550€ is too much. 300€ maybe is worthy