Anyway isn't there a possibility (probably related the increased output res and the 4 wire) that the higher output voltage may help piloting the transducers for high variable impedance headphones?
There is nothing to 'pilot'.
When the 6B difference in level is not present the voltages and currents are exactly the same.
The drivers are always balanced in operation regardless if one of the ends is referenced to ground or not.
The variance of impedance has no other influence other than drawing less current. Actually it isn't even that it technically is a counter EMF that generates a current in the opposite direction of the supplied one that are simply subtracted from each other while the applied voltage remains the same effectively lowering the drawn current and seemingly increasing the impedance.
An amplifier only provides a voltage. There is no difference whether or not this is created opposite a reference (0V) or opposite another voltage.
Besides... if it were impedance dependent balanced would not 'work' the way you think it does with planar dynamics nor with quite a few dynamics.
The only benefit of balanced drive is a higher possible max. output voltage where a power supply voltage imposes a limit.
The benefit of 4 wire over 3 wire is the most important aspect.
The common return wire which affects stereo effects/crosstalk is simply not present in a 4 wire solution.
The point is that even a TRS jack (which by definition has 1 combined reference) can still make perfect use of a 4 wire 'solution' even when the headphone itself has a single side entry. As long as that has 4 connections on the headphone side it will work just as effectively as a differential drive.
This is because the drivers are inherently 'balanced' in operation.
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