I have been wondering how XLRs in a phono cable and into a phono stage with XLR input works. (XLR plug to a Din end connector). My simple mind tells me the phono cartridge has 2 pins for tonearm wires per channel. The XLR plug has 3 pins/wires. Where is the 3rd pin/wire connected to the cartridge which has only 2 pins per channel? I understand XRL cables are 3 pins to 3 pins from input to output and vice versa.