>>106994380
Looking online, the EX5 uses a single TPA6120A2 chip (in a composite setup with an LM4562 to get better performance), which is a dual-channel headphone driver. No sign of separate negative channels in the headphone driver circuit.
The only difference on the spec sheet is that -88dB crosstalk for the 1/4" vs the -99dB for the 4-pin, which is still odd to me.