An impressive rotation of actresses — Maslany, Dizzia, Deirdre O’Connell, Tavi Gevinson and Julia Chan — is slated to inhabit A during the run: a clever way of signaling universality while adding box-office cachet in these uncertain times for theater. (More on that below.) An equally strong lure is, frankly, the gossip factor: Ireland’s own experience of domestic violence a dozen years ago in her relationship with the actor Scott Shepherd, when they were appearing in a show with the venerable Wooster Group. What makes “Pre-Existing Condition” so powerful, though, has nothing to do with that. It is A’s Everywoman nature, combined with the vulnerable physicality that’s so evident in such an intimate space: her breath, her welling tears, the placating smile she puts on like a demure piece of armor when she runs the risk of upsetting a man.