I was thinking along the lines of capacitance on the common return.. the circuit, not just the headphone cables. I misused the term crosstalk - mea culpa - I'm still learning
As you say, the headphone diaphragms themselves don't care, unless there's a perfectly sealed chamber between them... Eh... I'll give up on the airhead joke while I'm still ahead...
They'll play what is fed to them, and my concern is that what's fed to them may be somehow degraded -- the two channels pull and push against each other through the common return -- I just find it hard to digest that this common return is Hand of God stable enough to prevent the two circuits from interfering with each other AT ALL. I can see this logically possible in my head, but my id keeps going "but, but, but". (I do enjoy the conversation).
Full disclosure: I'm likely misusing telco analogies since that was a field I've worked in for years. I know tip and ring -- sleeve is alien in the world I come from
I've seen high capacitance on longer line runs and the use of load coils/inductors to offset that (you didn't really expect 56k with your modem, do you?). I understand the importance of line impedance for termination to prevent echoes/ringing. I have seen issues with bridge taps (basically extra wire on your circuit acting like a very good AM antenna and causing an impedance mismatch), and as often as not, results similar to a "single-ended" system by putting two circuits on three wires when there's a shortage of free copper pairs (the signal on each channel is entirely different, unlike most audio, and we can tell when this is done to a T1 by detecting errors in specific bit pattern tests). With the latter, I've probably seen the worst-case scenarios of the three-wire/two-channel system, but can only describe the symptoms and the fix or work-around rather than the actual physics employed in the problem.
Two channels - three wires - we always fixed that with two pairs, and in my mind I desperately want to translate that into the audio world, or at the very least rationalize the purchase of new Schiit!
If you haven't ignored me by now, what I'm grasping from you is that the biggest improvement technology-wise is in the connector...
Seems that going with a whole different breed of amp just to get a new connector is a bit overboard? Otherwise it just comes back to what product is engineered better (how boring is that?)