It's extremely hard to compare custom IEMs. Few users have more than one pair, so direct personal comparisons are rare. They can't be measured by InnerFidelity because they don't fit in the measurement head's ears. What to do?

Damn the torpedos, full speed ahead! In this review 5 InnerFidelity writers, blessed with the generosity of manufacturers willing to put their ToTL CIEMs through the ringer do a massive comparative review of 24 of the worlds best custom in-ear monitors.

Epic!

A few months ago we tested Logitech UE's new in-ear flagship, the UE 900---a top-tier, quad-driver earphone with very impressive sound quality. Continuing the budget theme of my recent reviews, I thought the company's cheapest armature-based model was worth taking a look at as well.

At the heart of the Ultimate Ears 900 are four balanced armature drivers with a three-way passive crossover. The design utilizes dual bass transducers and single drivers for the midrange and treble--a setup similar to that of the Westone 4 and many custom-fit earphones. Impressive as that may be, the UE 900 will need to provide a very compelling case for its performance in order to justify the $400 price tag.

The Logitech Ultimate Ears Personal Reference Monitors are truly bespoke audio, hand crafted just for you. They'll fit your ears only, the sound is your sound, with a tonal balance tweaked by you, for you. Accuracy isn't part of the PRMs raison d'etre, not in the slightest, it's pure audio self-indulgence. That level of customization doesn't come cheap, the PRM is $1,999!

If there is any one product to be credited with catalyzing my love of in-ear earphones, the HiFiMan RE0 is it. Over the years Dr. Fang Bian & co expanded the lineup to much more than just earphones, but the latest-gen RE-262 and RE-272 in-ears, like their progenitor, are audiophile fantasy through and through.

I should mention Tai lives in Malaysia, and a couple of the headphones he recommends are not available in the U.S. Thanks for the recommendations Tai.

I've spent a lot of time with good balanced armature monitors stuck in my ears. Mostly it's a pleasure --- there are some darn good headphones out there of this type: Jerry Harvey Audio JH13, Shure SE530, Etymotic ER4P, and Audéo PFE come to mind. I've also spent a good bit of time with in-ear monitors that use dynamic drivers. That hasn't been nearly as pleasurable.

Lately, that's begun to change, and with the Sony MDR-EX600 and MDR-EX1000 I'm thinking we've got a real horse race on our hands.