Efficiency might be the key since it could keep the loudness happening with less opportunity for your amp to strain. If you really want to get loud, stop messing around with hifi speakers and buy a pair (plenty of used stuff in your price range) of the largest pro PA speakers you can find along with a powered 15" or 18" sub...and prepare to be asked to move out of the neighborhood. This will allow you to have an alternate career as a DJ where you can meet hot chicks with tats and nose rings.