If you play a three-note chord (C, E, G), Trumpets 1 & 2 and the Trombone will double the same note. This sounds phasey and weak.
This guide covers version 1.4.2+ of Session Horns Pro. Always check for library updates via Native Access. session horns pro manual
Located on the far left. Here you control the balance of the five individual players: If you play a three-note chord (C, E,