here is a good video introduction on recording a grand piano
you can listen to 4 different stereo microphone/placement/techniques/patterns on a grand piano. you can switch the microphone setups while listen to the audio clip to compare.
click on "have a look" > skip the intro > language > Piano > choose the mic setup > play the clip
Recording a grand piano presents enormous challenges for many home recordists. Thanks for sharing this video that has great information.