The first (and only) Review of the ZX2 TRRS Mode (I mean c'mon, this is–slightly–ridiculous).
I agree with what everyone, including the designer of the ZX2, says about TRRS operation. It improves the R/L soundstage. The sound becomes–slightly–less center focused and–slightly–opens up the width, while retaining the center image. How much is "slightly"? The switch was actually the ideal way to test it, because I didn't have to swap in/out an adapter, I just flick the switch on and off. I mention that because without this method I just might've thought it was my imagination. That's how "slight" the difference is. It's not nothing. It's not marketing. It provided enough of a difference that Sony included the engineering, but not enough for Sony to brag about it.
Is it worth it?
If you have to A/B this closely, it won't be worth it for the casual ZX2 user in crowded cafe or on a jog, etc. But, then again if you have a ZX2, you are somewhere in the more serious audiophile camp, I'm thinking (after all, you're reading and I'm writing). In that use-case it's a game of inches. This is an inch. I think, for the bump in SQ, if it were costly or difficult, Sony wouldn't have thought it worth the effort. It's a similar situation in taking advantage of it. If it cost a lot or involved a lot of work, you'd have to think twice. However, for the price of a TRRS connector (great ones are $11.00) or professional retermination ($75.00) it's totally worth it, no-brainer.
Of course, the wrinkle in the no-brainer, is that if you reterminate, you can't use the same cable in regular TRS gear without an adapter. The problem with going the adapter route is you lose some of the SQ in TRS you've gained in TRRS by having to go through the adapter. That's why I put in a switch.
How to do it is pretty straight forward, but may be difficult to implement depending on your skills. You have to have some high quality wire, and solder one wire to the R- contact (which corresponds to the 4th ring from the tip/ i.e., the sleeve) and another wire to the L- contact (which corresponds to the third ring from the tip). Then you solder both wires to a SPST subminiature switch (or two leads of a DPDT). When the switch is "off" (open) it's in TRRS and L-/R- are separated. When the switch is "on" (closed) the L-/R- are bridged and form a common ground: TRS.
Hope this helps someone. For me, yeah, it's worth it.