I also have this problem with cache enabled. I get false starts at the beginning of playback, and both the beginning and ends of songs are clipped. I have to rewind to the beginning of the track after the song has loaded in memory to get unclipped playback.
If I disable cache playback, the problem goes away.
I have Amarra 2.1.1 and still see the problems. I have a Mac Mini with Mac OS X 10.6 Snow Leopard, 8GB of RAM, SSD disk, and 2.26GHz CPU.