When mixing two tracks exactly the same BPM (confirmed by pressing sync), I manually adjust the song in cue to match the beat of the song playing. Once I get the beat right, the songs slowly start to drift away from each other even though they have identical BPM. The software accurately determines exactly where the beats of each song are (and when they don’t, I manually edit the beatgrid to fix it), but nevertheless they slowly move out of sync. The only way I can keep a song in sync is by using perfectsync function, which defeats the point of owning decks. This happens with any 2 songs I play at the same BPM.