Originally Posted by james444
Well, sorry for being one week late with that, but here we go: JVC FX700 vs. Flat-4 SUI
Putting the FX700 on again, I'm instantly reminded of how their cable length simply sucks: 87cm (34") as compared to the SUI's generous 130cm (51"). Nuff said, SUI wins hands down in the usability department.
However, things are far closer when it comes to sound quality. Let's start with a fully sealed FX700 first: bass has a lot more impact than the SUI's, even though the latter are no slouch. Moving up to the mids, the FX700 sound significantly warmer and slightly recessed, whereas the SUI stay clearer, though not particularly forward. Moving on upwards, throughout the upper midrange and highs, the SUI start sounding thinner and sharper than the FX700, while presence is about the same. Top extension is excellent on both, at least till the upper limit of my hearing at 16kHz.
Looking at their overall signature across the whole range, the FX700 are rather a V and the SUI a U, but both IEMs have some disparity in note-weight, the FX700 being too weighty in the lows and the SUI too feathery in the highs. ymmv.
Now, wearing the FX700 with a loose seal (the way I actually prefer them), things change dramatically, and all of a sudden the two contenders seem much more similar. The FX700 lose a good part of their bass impact and warmth, but also a little note-weight in treble, which brings them overall quite close to the SUI. They still retain a tad more mid/upper bass though and I feel that the SUI's bass is more evenly distributed between mid/upper and deep bass. In the midrange, the FX700 gain presence and lie level with the SUI, but the former sound a bit sweeter and lusher, whereas the latter appear a little drier. The same impression continues throughout the upper mids and highs, where the SUI seem aimed at retrieving every tiny bit of detail, whereas the FX700 keep up with them in sheer resolution, but present everything in a slightly smoother and less analytical way.
To wrap up my impressions, while I don't feel that either of these has an edge over the other, my personal preference leans towards the JVCs, because their timbre is just to die for, especially with strings.
The SUI, while far from lacking in timbre, can't quite make my skin crawl like the FX700 in that regard.