Zarthanity777

So I got the Bogie Petrucci and I am a little confused......Amp Matching Pack-Settings Tab where it says Channel one says 3 then the gain says 4P. What does the P stand for? And if channel says 3 does that mean I set my channel volume at 3? You have to set each one of these presets this way? Slightly confusing. Also in the processed presets there are empty IR’s which IR’s do I add to those? The number at the end of the presets title? Please clarify.