The Track count is related to the CPU speed and the DAE Buffer setting:- 8 Track playback requires a 60MHz (or faster) CPU and the DAE Buffer set to 2 or higher.- 12 Track playback requires a 80MHz (or faster) CPU and the DAE Buffer set to 4 or higher.- 16 Track playback requires a 100MHz (or faster) CPU and the DAE Buffer set to 8 or higher.If the DAE playback buffer is set to the minimum setting, DAE Powermix will not show up as a valid playback engine.NOTE: Due to performance limitations on some CPUs (like the 7200 series), Pro Tools only allows up to 8 Tracks in PowerMix mode.