The ideal instrumentation is piano (MD), guitar (acoustic & electric, not at the same time), electric bass, horn, violin, and cello. Horn and violin are never played at the same time and could be played by a synth.
The show can also be performed with any paired down version of this, from just piano to piano/guitar, piano/bass/drums, piano/horn, etc. Only piano is required.
Orchestration for Instruments:
Piano
Drums
Bass Guitar
Guitar
Horn
Violin