What you witnessed at the German Festival was probably fueled as much by alcohol and the 'festival' atmosphere as by the band's volume and antics. If a 'bad' jazz group tried that in a jazz club, the 'excitement' you'd see would be the band getting tossed out on it's rear to a chorus of boos. You simply can't apply the experience of one music situation to another. Sheer volume can be as much of a negative as a positive, depending on the venue and the degree of appropriateness. Volume alone has little meaning until framed in context, and is certainly no guarantee of generating audience participation or excitement.

To me, the key isn't LOUD but clarity. Volume should always be just what is appropriate for that specific situation, but CLARITY (as in QUALITY of sound) is ALWAYS in order.

It may not be possible (or practical) to have the perfect (sound) rig for every musical venue so it's probably best to just get the best possible speakers that will best amplify the instruments in YOUR rig (including vocals)......then add 10% (if optimum turns out to be 1000w power amp and 12" speakers, get 1500w and 15's - okay, not exactly 10% but you get the idea).

......and finally, if you're going out specifically to listen to music, stay away from German Festivals.

chas