Well I have had it for 5 days now and I do have to say that yes, I am impressed. It is a lot better than an impedance adapter, at least in my situation of a Musical Fidelity M1 desktop amp powering my IE800 IEMs. I have found the ultra setting to be the best. At that setting, classical music with a very large dynamic range works with the volume control at around 11.00 o'clock (popular music around 9.00 o'clock) and there is no audible hiss whatsoever anymore - even with the source paused and the volume turned right up to maximum. The high setting is not as good - there is still some audible hiss (albeit very low) and the sound is not as coherent or smooth as it is on the ultra setting.
Compared to the impedance adapter it is no contest. The impedance adapter makes the sound overly flaccid, smoothed over and lacking in detail - almost with an euphonic vintage quality (but not in a good way) that really is neither my cup of tea nor is it true to the source. The IEMatch, however, seems to be as transparent as you could possibly get - the music remains focussed, etched and detailed but in a good way. I can't ever see myself using impedance adapters ever again having bought this.
On the negative side, even though it does what it says on the tin and does it very well, the Australian $99 price was very hard to swallow. Had it cost the Australian equivalent of the US price I would have been much happier. I also would have preferred a simpler single-ended version terminating in a male 1/4" stereo plug option since to me that would be how this device would be likely deployed in many cases. It would be interesting to know what proportion of purchasers use this as a true balanced connector from a 3.5mm TRS source to an IEM versus a single-ended 1/4" termination as I described. To be honest, I would be surprised if most customers used it balanced, let alone on a 3.5mm output. But perhaps I am just out of date and very wrong about that!
But ignoring those caveats for the moment, the best thing about the IEMatch is that when looking for amplifier upgrades in the future, I (nor anyone else) need never fear potential mismatches or the dreaded hiss factor when using IEMs. I can pretty much short-list any amplifier under the sun now, thanks to this device and that makes it a very worthy little piece of kit even just on that account. I had a couple of high end amps shortlisted for the future and had to ditch them after reading the reviews about the prodigious voltage outputs. Now there is no need to worry. If it can handle an M1 with an iE800, it should be able to handle almost anything.
