Well, which ones are you aware of? Give us something.
lazy, lazy, lazy
i haven't played with any of these myself, but looking at the plists there is:
- CategoriesThatShareVolumes.plist - seems to show how apple grouped difference sounds and volumes
- CategoryMinimumVolume.plist - this sets the min volume for FindMyPhone, PhoneCall, Ringtone, and TTYCall (and prob some others if you set additional categories)
- RegionalVolumeLimit.plist - seems to set a max volume systemwide
- SystemSoundBehaviour.plist - sets vibrate, ring, etc
- SystemSoundLowersMusicVolumes.plist - sets how much a certain event will lower the music
- SystemSoundMaximumVolume.plist - i think this is the one that really has the meat of what OP wants to change.
- SystemSoundVolumeAdjustment - i think this sets how much an up or down button changes the volume up or down (with 1 meaning no change, so .5 is .5 down and 1.5 is .5 up)
And so forth. look into the files and do what you want - just make sure to backup first!!!!