Just getting started on the Boss BR1600. Have 4 tracks of drums,2 guitars, bass, and vocals recorded on 8 tracks right now. We want to mix down the drums to 2 tracks(stereo). The manual is very confusing about this. According to the manual, all 8 tracks have to be bounced down to 2 tracks. Surely there is a way to bounce just the 4 tracks of drums down. Anyone have any experience with this? All help appreciated. Thanks!!