Sorry if this has been done to death already. I had as much of a search as my work commitments would allow me and I couldn't find anything on this. I know I'm opening myself up to the: "how long is a piece of string?" variety of abuse and it may be that that is the only sensible response to my stupid question...
I was wondering if there is any kind of a rule of thumb for how big a PA (in terms of wattage... or is this the wrong indicator?) one would need for a particular size of room and/or audience? I know that this won't be a precise science and will depend greatly on how loud you want to be.
As an indicator of what I'm after: we have a pretty heavy-handed drummer and all volumes are set against the drum which will not be mic-ed. Any help at all, however subjective and anecdotal (e.g. we use[*] and it does the job), would be very gratefully received