“Hush!” The ladies seated near me in the audience of Geffen Hall were being shushed by the row in front of them. They were chattily swooning in admiration of pianist Bruce Liu, making his New York Philharmonic debut in Rachmaninov’s Rhapsody on a Theme of Paganini, as he began his second encore of the night (a transcription of Bach). A rarely performed overture by Louise Farrenc and Dvorak’s Seventh Symphony completed the evening.