I have very little experience with headphones for music. My experience with McIntosh was with the MC 60s, the standard in psychoacoustic labs. As a grad student I did calibrate and match TDH 39s, another lab standard at the time, and served in lots of binaural signal detection experiments using the phones I had matched.
Headphones for sound control
I'll be moving to an up-scale life-care facility. The apartments have concrete exterior walls, and I usually listen to small baroque and jazz trios at moderate sound level, But I think headphones may be the way to go when I want to crank it up for large orchestrations like Aida or Mahler's 2nd.
I've been impressed with the sound of my cousin's Sennheiser 800S with his McIntosh headphone amp. I have an Ayer QX-5 Twenty with a headphone driver that Ayer tells me is very good. I suppose the answer is to try the Ayer before buying the McIntosh. I've downsized my rack of Ayer gear to a KEF LS60, but I really like the sound of Ayre electronics. Advice sought.