You're probably creating a psychological barrier effectively separating you from the edge, your beloved customers. This "podium" effect feels safer to stand behind than not.
Since busking is all about the interaction with your audience, I would suggest running completely around and even through them - "searching" for something you've "lost" - making sure to gently move them out of your way as you "search". Women excel at this because it's all psychological.
By embedding yourself right into the interaction, you can leave your table for your grand finale.