What a wonderful ensemble! The theorbo player is doing an excellent job of playing the bass line. At first I thought there was a gamba, and then of course realized there wasn't, and that it was the sound of the theorbo. The harpsichord looks like an Italian copy. I would love to know who built the instrument as well as the original instrument it was based on.
Dear danawinsor1380 thank you for your comment! Talking about the harpsichord, you are right, this harpsichord is based on an Italian model and it was built by Roberto Marioni.