Even though I have the earlier M3, the expanse of an orchestra, with the sense of string section here, basses, tympani, etc. can be thrilling. Dynamics are great as well as imaging. For myself, since I play records as well as stream (innous zen mini) I tend not to listen to classical except from vinyl. I find vinyl superior to my current setup for digital.
Everything else, (jazz, rock, soul, blues, world music) sounds great, and the Spatials and OB's have an openness that when you hear a band (or orchestra) it sounds more like being at a live concert--amplified guitars sound like amplified guitars, etc. The "richness" of strings or bass or orchestral sounds, I think will be determined by your amplification and dac, which is in itself another journey.