Like Jimmy, I've gone through a bunch of IEMs, including various custom molded ones from Future Sonics, Sensaphonics, and UE. I don't like the acrylic ones, because they don't really ever get a really good seal. Maybe they'd be better with the 3d scanning. However, the Sensaphonics, being silicone fit great and give me great isolation, which is important because one of the primary reasons I use them is to keep my tinnitus at bay as much as possible. But, they still don't sound all that great. They have a boost around 3-8khz and some weird stuff in the midrange.
What I use now are the Etymotic ER3XRs. They are universal fit and they are head and shoulders above all else I've tried in terms of fidelity and seal. The only downside is that they don't have a big low end. That's where the amp comes in, but you have to be careful because the seal is so good that by the time you feel the amp, it's really pretty loud. However, I have found that the EQ decisions I make with them are far better than all the others because the mids and highs are so perfect and smooth. Listening back to recordings, I realize that I'm not setting the filters on the bass to overcome deficiencies of the IEMs, but to get the appropriate tone for the song.
Sensaphonics are now making dual driver full range IEMS (the D2 model) and I am intrigued. Being crossover free and BA free, my guess is that they'd be smoother throughout the midrange and also not super hot in the high end, which triggers the tinnitus.
One of the best things about the ER3XRs is that they are only $175 and they are also fantastic for listening to music (their primary function), so you can buy three pairs for the cost of one custom IEM. But, they are not good sounding for the money, they are just good sounding.
They did just come out with a dynamic driver version, which was at Massdrop for $150, so that seemed worth a shot for a backup pair. I'll get them later in the month and can report back, if anyone is interested.
For all Etymotic, get the XR version, not the XS. It has better bass. The bass isn't absent, it's just not hyped like 99% of IEMs. Another benefit is that the low end is what pumps pressure into your ears and can cause damage because you don't know how loud it really is.
I find that Westone OTO-Ease helps all IEMs get a good seal, too.
Greg, it's good you abandoned the one ear in one out thing. That's the fastest way to permanent hearing damage.
