Welcome @GaryS!
There appears to be 2 classical music threads, and this one hasn’t been used in a long time. We’d welcome your classical music insight in this thread instead: Classic Music Discussion
And your headphone question would probably be better in the General Purchase Advice thread. I’d suggest posting the question again there, and maybe be a bit more specific about what you’re going to be plugging the headphones into, e.g. you mention a DAC/AMP, and presumably that’s a portable one? That will help the experts help you.