We did this Ephesus evening concert excursion on a Seabourn Sojourn cruise in 2013 which was included free of charge then. It was held in the street location in front of the amphitheatre and the Aegean Chamber Orchestra gave an excellent classical concert. It was a magical experience on a beautiful evening as the sun was setting..We had an early dinner on the ship and then had wine and light refreshments served at the concert.
I posted a video on Youtube of the call at Kusadasi. and the Ephesus concert begins at 8.50, as the first 8 minutes is Kusadasi and Seabourn Sojourn lunch.
** - Sorry but the link starts near the end of the tour as we return to the ship, but the concert is from 8.50 to 21.50