When burning-in the K702 Annies with pink noise overnight (with them off of my head), I noticed that the regular K702 leaked more than the K702 Annies. This was noticeable, at least to me. And yes, the volume of the headphone amp was exactly the same, and yes I'm aware of the physics involved regarding closed-back phones. Extra bass and low impedance closed-back phones are preferable when walking outdoors in a city.
I thought that the regular K702's had more shouty upper mids (annoying & more fatiguing) than the K702 Annies.
Teac UD-501 drives the K702 Annies just fine. More than half on the headphone volume knob is the maximum for me!