As you get more into high-end in-ear monitors (IEMs) it is not unusual to encounter discussion online that you need amps or DAPs that have a low, or near zero output impedance, or people talking about how much noise they hear hiss or noise with certain IEMs. The iFi iEMatch (2.5mm version linked. 3.5mm version is also available) is designed to deal with that when your set-up is less than ideal for the IEMs you have bought.
My example for this review will be Campfire Audio’s Andromedas, which have two of the most common problems that IEMs can have. Firstly, they use multiple drivers, which means that their impedance isn’t flat. That means that the impedance for the bass drivers isn’t the same as that of the mid-range and treble drivers. While this isn’t a problem with most new DAPs and amps, some devices, such as my old iPhone 6, or the new Hiby R6 have a high output impedance. While this reduces hiss, when used the Andromedas, the result is less than the usual amount of bass.
The iEMatch helps with this as its two settings, “High” and “Ultra” set the output impedance to <2.5 Ohms and <1 Ohm respectively. The question here might be: Why not just have the iEMatch use “Ultra” mode only, as it’s technically supposed to be the most ideal? The problem with that is using the iEMatch attenuates the signal significantly, so with some devices their may not be enough volume range left afterwards to get an ideal listening level.
The other issue the Andromedas and other IEMs have is sensitivity. This is a measure of how much power is needed to get to a certain Sound Pressure Level (SPL). It might seem that the higher this is, the better, but the consequence of high sensitivity is that the IEMs will pick up residual noise (hiss) from the electronics more easily.
A good example of this is if I try and use the Andromedas with the ALO Audio Studio Six. The amp was not designed to be used with IEMs at all, and this is readily apparent when I plug the Andromedas in. There is a LOT of hiss, enough that it is clearly audible even while music is playing. What is more, there is almost no usable volume range. Even when I turn the volume up a tiny bit it is already too loud.
With the iEMatch plugged in, on “High” mode the hiss has mostly disappeared, with only a tiny residual amount. In “Ultra” mode it has gone completely (at least as far as I am able to hear) and there is now some usable volume range.
The iEMatch, while a bit bulky, also nicely comes with a small bag and a pair of 37dB isolating ear plugs.
Overall, the iEMatch is a handy device for when you need to get a pair of high-quality multi-driver in-ear monitors working with gear that isn’t optimised for them.
Thanks to iFi Audio for supplying the iEMatch for review.