If the record player is equipped with an earth lead connect it to the GND terminal of the unit.该电唱机如备有接地线，则应将它与本机的接地端子连接起来。
The uncommitted op amp has its noninverting input connected to the GND pin.闲置(我理解，看你的应用场合)的放大器反向输入端要接到地上。