I know the thread is titled "Kilt knights” but what would one wear to see the Pipes and Drums of the Royal Scots Dragoon Guards when they are performing at 1500?

I have a good SWK in Black Watch and I might get my US Army tartan in time from Rocky. I already know that I should wear an all black or brown sporran with coordinating shoes, and belt. However, what else should I wear without looking too dressy or too casual for the occasion?