I've seen that before, and in a perfect world, eliminating that last bit of wire would be the ideal. Like with any hardwired headphone. In a slightly less perfect world, I think the way it works is that length is the killer in cables. Even the worst cable isn't much liability at an inch, or even six. It's as the runs get longer that it becomes more of an issue. So (the cable theory, ignoring my stance for a moment), the idea is that the 5, 10, 15 foot run you have from the amp to the driver jack has far more effect on the sound than that last 1" will have. If you can get a "perfect" signal to that last 1" there's not much that can go wrong from there. Imagine tethering your headphones to your amp with a 1" cable. Even AKG's nasty wires would be suitable.
It's for that reason that balanced was invented...because in pro audio the losses that start appearing after 25ft or so, and only after that length matter. Under that length there wasn't a reason to balance it.
Also I think the two big things in cables (again going from the cable upgrade theory, ignoring agree/disagree stances, and especially for long runs, some of this is absolute fact) the biggest issues are about keeping the ground/return separate. Really cheap wires (AKG!) don't even bother shielding the cable or the conductors and share a common drain wire which can introduce crosstalk. The Senn cable at least keeps the drain wires separate, but for a 10 ft cable or so there's still plenty of room for crosstalk which better shielded cables can prevent. Once you're up to that last 1" of wire in the driver mount, attached right into the voice coil, those wires are kept 1/4" apart from each other or so, far more spread out than in a cable jacket, so there's no real chance of crosstalk between signal and drain, and since they're on opposite sides of your head, zero chance at all for inter-channel crosstalk.
Whether you do or don't believe in boutique cables, those details can't be denied between cheap stuff and even $1.50/ft bulk wire like Belden and Canare, and the physical difference between a jacketed 10ft cable run carrying both channels versus the 1" of very visibly separated wire (not cable) in the driver are obvious. There seriously is no real chance of anything going wrong at the plug, SQ wise.
I was talking sound signature, not necessarily sound quality, sorry for the confusion. I mean, would the sound signature change if it's going through the same piece of wire to the driver anyway? Or would it change some and then the SS of that bit of copper wire changes it again?