Here's my advice (I'm not an audiophile and my english is poor, sorry)
After more than 50 hours of burn in, I decided to comment about these FXT90. I was looking for some fun sounding IEMs, though I'm actually more into balanced signature.
I used them mostly on my Rockboxed Fuze with double flange silicon tips (they look the same than those from Meelec), I listened to 256 and 320k mp3 and Flac files.
First thing I noticed, this engaging sound comes from the overall timbre giving a sense of brightness, of sparkles sometimes, but with no fatigue, and from the bass impact.
The sound is not as warm as I expected, in a good way
, soundstage is average in width and good in depth, make me feel I'm close to the scene, instrument separation is fine. Bass is deep, punchy, tight when needed, not overwhelming, very well defined and controlled, mids sound natural, but it seems upper mids are a bit forward, it's really noticeable with female vocals, highs lost their harshness from the beginning, they're crisp, full of sparkles, but far from being sibilant and they're not as extended as they are with Brainwavz B2.
I can say these earphones are very dynamic and powerful, they're fun but also fatigue free, my only complaints, I'd like them to be a bit more spacious and detailed.
I rank them just behind the B2.