It is not too large or too loud. You should give it a try!
As theaters go, I would consider this a more autistic-friendly venue. This is a small venue of less than 100 seats, and seats are not assigned, so until the show starts you can move about and choose a spot that is most comfortable. Each seat is of a good size so you aren't sitting against a stranger even if they are next to you. Depending on the show, the audience might not be full, which adds to your options. The distance from the seats to the exit is short, so if one became overwhelmed, slipping out to the fresh air is an option. They dim the audience lights and use a sound system for music and effects, but the performers are not usually using microphones, so it isn't overly loud. Most shows have a cast of 12 people or less.
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