Ok, how simple can you really get?!
I think this is pretty much it with wearing a basic white tee and some skinnies. It's always hard to decide what to wear when attending an audition and choosing what would be best for that particular call. You definitely need to be comfortable and be you!
Give it a try sometime, honestly any solid color will do, and instead of throwing on the usual pair of sneakers or comfortable flat try a simple boot! I promise it'll change the look of the outfit completely. These are BP from Nordstrom, but I believe these exact ones are sold out... they were a super hot item this fall/winter season. I have an almost identical linked HERE also via Nordstrom. Or if you like the leather look instead of suede BP has these new ones in, click HERE.