I have heard both these amps at length. I currently own both the Halo A23 and the Anthem A5, which are the little brothers of the A51 and P5, respectively.
The A51 is class A at low levels, and it has many of the benefits associated with class A, including a "smoothness" that is very pleasing. The P5 is perhaps a touch less refined, but it is a powerhouse. For music, I would probably select the A51. For movies, the P5. But both are excellent options.
The A51 is class A at low levels, and it has many of the benefits associated with class A, including a "smoothness" that is very pleasing. The P5 is perhaps a touch less refined, but it is a powerhouse. For music, I would probably select the A51. For movies, the P5. But both are excellent options.