The JVC FXT200 is a decent IEM. Really extended highs. Reminds me of the RE0. Clear, lively, and slightly sibilant. The bass is sublime. Probably the best bass of any IEM i own. It's even got more presence, texture, and speed than my XB90EX. Mids are dark and thus the overall presentation is v-shaped, but not pronounced. Soundstage is average. Imaging is good. Timbre is natural, but there's just a sharpness to the sound that reminds me of a BA driver. If I was going to compare it to another IEM, I'd say the closest one I could say is the VSonic GR07BE, but with far better sub bass, or the TTPOD T1E, but again with better sub bass present. These are great for metal music, and can keep up with really fast passages. The bass is a bit much though. It's got slam. This also reminds me of the FX850, but with far less stage, not nearly as 3D, and with less depth.
These are meant to be a successor to the FXT90 and a less intrusive FXZ200. It pretty much sits right in between those sonically and aesthetically. Less sibilance than the GR07, but bit more than the T1E. it's got a great deal of clarity for having such meaty mids. Instrument separation is good, but detail retrieval is average. I'd say it's equal to the s-018 in details and separation, but the s-018 has less extention in the highs. I'm not sure if these will remain in my rotation, since I think for the money, the T1e is probably a better sounding IEM, with less sub bass/mid bass. maybe I'm just used to the more controlled bass of the A83 or the Singolos? Either way, it's better than the Sony's, but not as good as the A83, so I'd save my money for the T2 or the A71.