The title "one of the best classical music headphones I've ever heard" was construed to mean that. My apologies if I misread your statement.
And not trolling, just snarky.
The resonances and soundstage issues most closed backs have would seem in my opinion to make them a poor choice for classical. My 880's are semi open and still leave room for improvement in that category.
i think the thing that leaves a great impression on me about the 660 is that its not the "normal" closed back headphone.