Hey, like the real sound guys say, "Fill up the space and no more..."... Busking isn't like some exhibitionist thing... So, hey, if yer space is only 20 to 30 feet deep and you need a little amplification to fill it then do it... Nice little 7 watt battery operated Pevey do just fine... Don't need no Marshall stack...

Music and martial arts is similar that way... Minimum force to get the job done...

B~