There are certain things you need to keep in mind:
- The place has to be roomy enough for a proper flow of audio.
- The microphone diaphragm needs to be fragile enough.
- The lid of the piano should be open for a fuller audio signature.
- One microphone should be close to the string and the other one should place at a decent distance to cancel out any ambiance artifacts.
- The mic that’s further away should have a minimum 3-time distance from the closest microphone.