Jim, Originally, the stereo version, but my mono box set arrived later today and I listened to Rubber Soul, Sgt Peppers, and A Hard Days Night in MONO. The mono versions are excellent and the difference between the mono and stereo mixes are very pronounced in Sgt Peppers. The new mono remaster of A Hard Days Night overshadows the 1987 mono version by far. The remasters have more body, clarity, pacing and resolution. When I listen to the 1987 versions, it's as if I was listening through a door and the new remasters has put the music right in front of you. I am both happy and impressed with the remasters!!