Review - Kiwi Ears Allegro


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This page is aimed to clarify any questions or queries regarding the measurements and info posted on SoloSpec & Squiglink.

Click here to visit the Solo Spec channel on YouTube. The channel is just a host for videos showing basic specs (explained below). There is no commentary or opinions in these videos. For subjective reviews, see the Acho Reviews home page by clicking here.

NOTE: Due to the current backlog of reviews, the SoloSpec YouTube channel is way behind schedule. I will be making an effort to bring it up to date, with a large amount of content that needs to be edited and uploaded, but for now, I apologize for not keeping it up to date!

Click here to visit the Acho Reviews Squiglink. Here is a database of frequency responses for each of the IEMs I have measured. The site contains tools to allow you to compare them against each other, against target curves (not only the Acho Reviews target but also from other reviewers), and also access databases of measurements by other reviewers such as Super* Reviews, Bad Guy Good Audio Reviews, Audio Discourse, etc.

The Squiglink has been made possible thanks to Mark Ryan (MRS) from Super* Review. There is an interview with MRS published here on Acho Reviews and if you haven't checked out his channel, you can find it here: Super* Review.

Click here to visit the Acho Reviews Squiglink Isolation Database. Here is a new collection of measurements that I have been working on. You can see how much isolation each model of IEMs provides, compare them against each other and also reference things like earplugs in comparison.


First, I just want to clarify that, while every effort to make all content constant, the tools used for measurements are not precise laboratory devices, it is possible that errors may occur. 

It is also recommended that measurements posted on SoloSpec or Squiglink be compared only with other measurements also made and posted by me. This is the only way to be sure that the measurements are comparable against themselves as other measurement rigs may (will) differ, as may things like curves, averages, etc.

Published Specs…

These specifications are found online and are published as found. Sometimes these will be screen shots from a website or other times they will be copied into a text format. 

The specs are taken from official websites when possible but as these are not always available, they may be taken from other major sites.

The bottom left shows the source from which the specifications are sourced.

Weight and Dimensions…

The weight and dimensions are taken with calibrated scales and calipers respectively. While these are calibrated and are checked periodically, it is possible that small errors exist. These should be considered as general information and not exact precise measurements.

In the case of IEMs, the weight shown is for 1x IEM without a tip or cable attached, unless stated otherwise (for example, in the case of IEMs with a fixed cable).

The A, B and C dimensions are shown on the image published, these are taken with a digital caliper showing two decimal points but are rounded to the nearest decimal point.

The depth of the IEM is the longest dimension from the tip of the nozzle to the faceplate, not necessarily respecting the angle of insertion.

The length of the nozzle is measured from the end of the nozzle to the furthest point where it is understood that a tip may reach.

The diameter of the nozzle is the external diameter at the insertion end.

FR Measurements…

The FR measurements for IEMs are taken using a IEC-60138-4 /IEC711 compliant coupler. This is a coupler made to industry standards but may (will) still differ from coupler to coupler, therefore, it is again recommended to not compare measurements taken by different people on different measurement rigs, although every effort has been made to make sure that these measurements are as close to other known measurement rigs.

These kinds of couplers create a resonance frequency (resulting in a spike on the graph) around 8kHz, depending on the insertion. Above this point, the measurements are also not as accurate and can easily result in different measurements on different rigs and at different times, therefore, above 8kHz, the measurements should not be considered exact.

All measurements are taken using the same cable (in the case of IEMs with removable cables) and the same type of foam tips (unless noted otherwise on the graph), this is to help with getting consistent seals and better results (in the case of tips, in the case of cables it is to avoid certain comments ;) ).

When comparisons are shown on Solo Spec, such as IEM vs Harman2017 or IEM A vs IEM B, the measurements and targets are always aligned at 1kHz. This is not relevant on Squiglink as it can be adjusted to taste.

1/48 smoothing is applied to the measurements to clean up any small interferences but no further smoothing is applied. 

No averaging of the measurements is done, the measurements shown are actual measurements of the product in question. I make a minimum of 5 measurements per side, discarding the outliers and keeping the measurement that is approximately central and consistent to other measurements of the product.


The targets shown are for reference purposes only, this comparison is not to show if an IEM is good or bad, simply how it compares to the target curve shown.

The targets shown on Solo Spec are the Harman IEM Target 2017 and Acho Reviews Target (A.R.T.). On Squig Link you can choose the target.

The Acho Reviews Target is simply a reference to the response I am personally happy with. This does not mean that I dislike anything that deviates from this target, it is simply a reference point.

Please note that the A.R.T. is based on the Antcurve (Antdroid’s personal preference target) that you will find referenced on Audio Discourse, however, the A.R.T. has a slightly more elevated subbass that the Antcurve. The Antdroid target can be selected on Squig Link.

Isolation Measurements…

These measurements are taken by playing a sweep through a speaker and comparing the results of open field vs the results with the IEM inserted. 

In SoloSpec YouTube videos, the graph starts at 70Hz and is from 0dB to 105dB, with a 3M Foam Earplug as a comparison. Each time an IEM is measured, the open and 3M measurements are taken again to avoid any differences in placement or external influences.

On the Squiglink Isolation Database, the results show are negative, in other words, how much the IEMs dampen the sound in comparison to an open measurement. The graph shows +10dB to -120dB and the Zero Isolation Line (grey dotted line) is the Free Field reference. In other words, how far below the dotted line the IEM line is, is how much they reduce sound at that frequency.

Again, these measurements are taken with foam tips unless noted otherwise on the graph.

Subjective opinions and reviews…

The aim of SoloSpec is to not include any comments, opinions or subjective reviews, just the data so that you may interpret it.

If you would like to read subjective reviews of the items shown on SoloSpec, please visit

Other measurement resources…

As I said, it is not a good idea to reference measurements published on SoloSpec, or the Acho Reviews Squiglink, against measurements from other sources, as these may differ. Therefore, as the content of SoloSpec and the Acho Reviews Squiglink is limited to those products that have passed over my desk, there are other sites that can offer many more measurements and possible have measurements of the same two products you are looking for, taken on the same rig.

Here are some of the measurement databases and sites that may be of use:

Audio Discourse (can also be accessed from Squiglink)

The Headphone Show (coming soon)

And measurements from many other reviewers are available through Squiglink, such as Super* Reviews, Bad Guy Good Audio Reviews, Precogvision and many others.