Kristian Zuzek - Carved in Stone

This is sort of a dual purpose post. This is an initial mix with tracks I think I have to retransfer from my ADATs. I am using a MOTU 2408 mk1 and two ADAT XT20s. Problem is that I think there is a syncing problem. If you listen at around 1:00 I can hear this cyclical cracking sound. Does anyone know where this is coming from? At the end also you would hear more of it but as i fade the drums out you can only catch a bit of the sound.

Now to the juicy bits.

Drums: Overheads Crown CM700s, Snare SM57, Kick AT D2500 (OLD drum mix pack), the toms on this mix are muted so the toms are coming from the overheads.

Guitars: Main electric SM57, Acoustic AKG C414, electronic bit & ending electric guitar AKG C414

Bass: Direct

Vocals: Marshall V69