Ultimate Ears have definitely succeeded in creating something unique with the IERMs. From a discerning listeners point of view the IERMs have a lot to offer and for those looking for a set of in-ears to do their high quality classical recordings justice these should be on the short list. The tonality and the detail oriented sound make the IERMs a thrill to listen to. Ultimate Ears have mastered a few very hard challenges with the IERMs: timbre, treble and spacial coherency. The IERMs provide a level of midrange quality that the other high-end custom in-ears simply cannot match.
And while Ultimate Ears and Capitol Studios hit the nail on the head in terms of the tricky bits, some of the fundamentals are off by a touch. The bass is there, but quantity wise it is still a little shy of being perfectly level, and the roll-off does not make the bass experience any more thrilling. While the less powerful bass is forgivable for a detail freak like myself, it might be a tough pill to swallow for the general bass loving music enthusiast
The newly devised cable system is nothing short of smart. For years the fragile connectors used having been causing headaches all over the world, and this seems like the first wholeheartedly attempt at solving it. The solution is non-obtrusive and solves both microphonics and durability related issues.