Your Mac most probably doesn't use the same circuit for the headphones as it does for the speakers. It probably (like most components of this type) use a lower quality op amp to drive headphones. I, therefore, recommend the use of a seperate headphone amp.....much higher quality with no problems.
Headphone output on the Mcintosh C2200
I recently purchased a new Mcintosh C2200 (Frank Gow commemorative) from Audio Classics. I am extremely happy with it but find that the headphone output seems to be extremely low (I ahve to crank the level up to 60 or so to really hear it. Is this normal ?. Many thanks in advance.