Fab4 seems to play more samples for each MP3 track than do ip3k players. This is most obvious when playing synced as Fab4 has to skip-ahead to resync at the start of each track.

I have looked at the code and I cannot see how Fab4 could be calculating this differently to ip3k but I am pretty sure it is happening.

I have not tested this but I expect that it will also affect gapless playback.