I can now see why even after all this time the HD 650 is so well thought of even if someone prefers a different sound signature. They are for total sure different than the HD 560 II's I been using for 20 years. But at the same time not always better.
I think the 560 II are more detailed honestly. BUT their downfall is basically it seems to me while 560 II have more detail and clarity in the highs that are beyond anything I've heard, they fall short on bass badly compared to the 650's. Which in turn is why they are clearer highs and more detailed. But the HD 650 is much more musical, that extra hint of bass throughout gives 650 a overall balance that seems like it's what things are supposed to sound like. It's like 560 II's are a detailed examination of the music in clarity and the 650 is a laid back listening to the overall precision as it all comes together, it's like the entire thing becomes whole. I find myself with the 650's saying oh yea that's exactly how that instrument sounds playing that ..
I probably seem like I'm rambling and it's probably what many have known here for years, although the HD 560 II's are a rare breed from a time before today's market took off. But they are still a very special pair of headphones.
Oh and the HD 560 II's are still the most comfortable headphone I've ever had on my head. The 650's are nice in that regard but they aren't as plush soft and comfy as the 560 II's were for sure.