Just because u have 900 watts doesnt mean you have to use them. If someone is too loud tell them to turn down, or else it becomes a volume battle. You can learn to use volume at any level
If your amp is farting or clipping you can try everything else but the chances are it's not big enough for your gig, life is too short for bad gear and if it's not loud enough for you then that's what it is.
...or I am depping in with a loud band
What does this word mean, subbing, filling in?