I finally have my Flex Twins in my ears. After a year and two companies, I finally have CIEMs.
Please take my first impressions with a grain of salt. I would consider myself an audiophile, but not an overly critical one. I do not believe I am trained enough to make expert observations, I mainly go with what I like.
And in this case, I LOVE it. The fit is perfect. I'm a bit chuffed since these are my first CIEMs AND I did the impressions completely by myself. It took a little bit of learning on my part on how to get them to fit properly. At first I thought I would have to have the left side re shelled. But alas, it was just my lack of knowledge. the isolation is on par with my Etymotic MC5s with triple flange tips. Definitely enough to drown out any other noise with music playing.
The sound is great. I have not had a burn in period, but will do so tonight/tomorrow. My everyday headphones prior were Etymotic MC5s, which are a bit brighter and analytical. I tend to like the Etymotic style of sound. I also have HE-300s for my desktop rig, and I would say the Twins are closer to that. And there is nothing wrong with that. The bass is much better than the MC5s, but not overpowering, like with my MEE A151 or M6. With those, the bass was too overpowering, and much too muddy and I found them impossible to listen too. I would consider these more fun, a bit more lively. The soundstage is fantastic, the best of anything I have, other than my actual desktop speakers. Like I said, I do not have any "super" audio products and I cannot give a really good description compared to a gold standard. But in this case, I find everything excellent. I am looking forward to many many hours of great listening.
If you have any questions, please let me know. I will answer to the best of my abilities.