If you're thinking about auditions, consider a “technical” audition for any of your open positions. A technical audition provides you a little insight into a candidate's functional skills.
If you're hiring a developer, ask the candidate to extend a design, or find a problem and design a solution. You could ask a tester to test a piece of a product, or a particular set of features.
A particularly good technical audition is one where you always ask the candidates (for a certain role) to perform the same kind of work. Ask each developer to write some kind of code, or ask a tester to test some specific product. (Don't vary the task between candidates.)
You can use these auditions for a phone screen or an in-person interview.
Consider technical auditions the minimum entry point for auditions. You'll learn a lot about a candidate with this audition.