This house has no pit. It never had one — a thrust stage and an orchestra pit are close to mutually exclusive, because the pit has to go where the front row of the audience is standing.
The options
There are three. Put the band offstage and relay them in, which turns live music into a very expensive recording. Amplify them from the wings, which puts the sound in a different place from the players. Or put them on the stage in the light and let the room do the balance.
Why the third one works here
412 seats, the furthest 17.5 m from the stage edge, and a ceiling that was designed when people expected to hear unamplified voices. Nine players at a natural dynamic reach the back of the gallery without help. We checked with the actual band, in the actual room, before we committed to it.
What it costs
Nine chairs, nine stands and a harpsichord have to come off the stage in the ninety minutes before another play goes up. Hilda Sowerby has views about this.