That’s what I was thinking.
This is what the manufcaturer said:
“I assign the current version to the use of the USB-C 3.1 connector. This solution will also allow, in addition to using purely analog inputs, in the future, to use all the digital capabilities of this interface and use the DAC and amplifier built into the headphones. In addition, it is the only solution that physically fits into the ear pads without additional metall tides.”
I know it’s been a year already but this question urges me.
So let’s say I want my Philips Fidelio X2HR to be balanced. Standard it uses 3.5mm TRS on both ends, if I want it to be balanced, can I use a custom 3.5mm TRRRS cable on both ends? I read somewhere
that the headphones doesn’t matter but just the cable, so I’m confused because you wrote that it is already determined in the cups (At least in the DT series).
You would have to mod the fidelio x2hr If you want it to be balanced. The ground (the negative side) is common between the 2 drivers (like on the Beyer DT wave was talking about).
While the drivers do not care if they share a common ground, a balanced amplifier will and it can damage it. If you have a pair of headphones wired up to be able to run balanced then yes you can just swap the cable and run them unbalanced… you should not go the other way.
Aight thanks, wasn’t going to anyway :), just theoretically.
If by “bal cable” vs. “SE cable” you mean 4-wire vs. 3-wire (Y-shaped GND or “return” wire), yes, there absolutely is an advantage: it reduces crosstalk between the L and R signals by a mathematically demonstrable amount. So it can get you some part of the benefit of “going balanced” without actually “going balanced”. But you will probably not hear the difference if the drivers have hundreds of ohms of impedance (those are already good enough at rejecting wire-generated crosstalk, they don’t need extra help).
I mean: balanced cable(2 grounds?/TRRS), with SE/3.5mm jack/termination(2 pole/TRS), going into a SE amp, to be clearer.
I haven’t heard any difference yet, with all my low ohm IEMs.
This is basically what a modular system for IEMs dose. A balanced cable to a balanced or SE jack, to a balanced or SE source. With a SE jack to a SE source, there is really no difference to that vs a non modular cable. Both tie the grounds from each IEM together.
Difference vs. what? Do you know for a fact the old cable you were using was 3-wire with a Y-shaped return/GND? You might have always been using a 4-wire cable, just that nobody thought to call it “balanced with TRS termination”, it was just a well-made SE cable. 
Yes, but it’s not all the same where you tie the grounds together: near the drivers (followed by a long common ground) or near the jack (very very short common ground, with very low resistance, allowing way less crosstalk through the voltage divider). Again: non-modular cables have also often been made with 4 wires all the way to the jack, just that nobody thought to call them “balanced”.
True, I was mainly talking about IEM cables where I guess you could tie the grounds together at the Y split, but I am pretty sure almost all are tied together at the jack. It is just that modular cables have the option to have the ground remain separate.
SE cable, with hard-wired 3.5/SE termination. (~$20-50 cable)
VS
Bal cable(hard-wired 2.5 termination), with 3.5 adapter jack. (~$33 cable)
Noooo clue about any of that haha.
If you can’t see the wiring structure from the outside there’s a way you can tell with a multimeter.