I think that it is important to have some regulation of the power of amplification if buskers are not behaving sensibly. Over amplification effectively shuts down the street for fellow buskers too - which is outright selfishness. Ideally, buskers should regulate themselves. However, when this is not happening, I have no problem with a fair set of rules. Any busker should know twenty songs or twenty different pieces. The worst places to play are those which are overplayed by very poor (and sometimes loud) acts. Places where the public expect the entertainment to be good are a pleasure to work in.