Glai, Usually you will want pin 1 tied to the tone arm ground. This would then also be the ground connection of the phono section. While there may be no difference in noise that you can hear, this will eliminate loud pops that can show up due to static discharge.
Furthermore, there is no sonic advantage to floating the shield. The phono cartridge and the balanced cable form a low impedance balanced line and so is relatively immune to cable capacitance and cable artifact, as long as the cartridge is loaded with some nominal low resistance (1000 ohms or less). If this is the case what you will find is that the difference between cables is literally gone, and the need for an expensive cable with it.
Furthermore, there is no sonic advantage to floating the shield. The phono cartridge and the balanced cable form a low impedance balanced line and so is relatively immune to cable capacitance and cable artifact, as long as the cartridge is loaded with some nominal low resistance (1000 ohms or less). If this is the case what you will find is that the difference between cables is literally gone, and the need for an expensive cable with it.