mute group - makes sounds cut each other off when triggered

why use this:
- realistic hi-hats (closed hat cuts off open hat)
- only one of several sounds plays at a time
- simulates how real instruments work

setup a mute group:
1. [shift] + [sound] → navigate to GRP page with [-/+]
2. pads blink if they have sounds assigned
3. press pads to add them to the mute group
4. now those sounds choke each other

classic example - open/closed hi-hat:
1. put open hat and closed hat in the same mute group
2. when you trigger closed hat, it cuts off open hat
3. sounds like a real hi-hat!

limitations:
- only ONE mute group per group (A, B, C, or D)
- all selected pads share that one choke group

to remove from mute group:
same GRP page, tap the pad again to deselect