I'm looking to buy a new amp for my keyboards, and I was wondering if there's a formula I can use to help me calculate some of the objective specs I should look for. Something along the lines of: I usually play on square-room venues, of A' x B' dimensions, for C number of people. What wattage does my amp need to be loud enough for the room?
Of course, this doesn't account for the subjective "feel" of the amp, but I'm wondering if such a formula exists.