Hello,
I also use the MP3@64 device on the internal clockport of my A1200, rev1D4, with Apollo 1240/40. I also experience some sound skip when playing back, but only on MP3 with bitrate 192+. Below this bitrate, there is no sound interruption at all. The sound quality is very good. Typical load on CPU during playback is 25-35% with Amplifier.
Regards
Alma