I have used a lot of amplifiers. Large ones, small ones, wall-powered and battery. I am going to share a secret device in my inventory. It is a portable amplifier that is powered by a lithium battery and is loud enough for hundreds of spectators. It is the Hisonic HS120B Lithium Battery Rechargeable & Portable PA (Public Address) System with Built-in VHF Wireless Microphone, Car Cigarette Lighter Cable, Carrying Bag ,1 Hand Held +1 Body Pack.
I have used this on Bourbon Street in New Orleans without any issues. The bars around can hear my voice inside clear without any distortion. This amplifier does get people asking about it all the time. My friend, a juggler also bought and uses one himself. One of our favorites is the included car charger. What a time saver. I have seen similar products for $300-$350. This is, at the time of writing, only $99. Do yourself a favor and look at the Hisonic Portable PA and welcome a great weapon to your competition.