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IMR Opus Mia review : The expansion king

IMR acoustics, known for their craftsmanship and tuning abilities have been making some of the best earphones in various price segments. Recently they have refreshed their lineup with 5th generation of earphones with their unique driver systems intact. IMR has adopted a newer design language too, it now has a slightly triangular back plate with a ports.

The 5th gen has the Samper (black) leading the way with the 5th gen Aten driver + 5th gen piezo ceramic driver paired with 3rd gen planar and dual ES drivers. Samper is priced at 1100 GBP. The PB TWO (successor to the original PB, blue) has dual ES drivers paired with 12mm planar and 9mm titanium dynamic driver with neodymium motors and is priced at 795GBP.

What I am working on here is the Opus Mia which is the soul successor to the R2 Aten. It houses the 5th gen dynamic and Piezo drivers but improves the sound by adding two ES drivers and comes in only one color, gold back plates with chrome body. It is priced at 600 GBP and faces tough competition from a bunch of earphones from Fearless, Dunu DK-4001 and many more.

In their words:

“The Opus Mia quad driver hybrid electrostatic represents the culmination of 3 years of development of the Ceramic Hybrid Aten driver (5th generation) now with the addition of a dual drive electrostatic driver with in built amplifier.”

Get one for yourself from here:


The Opus Mia comes with a lot of accessories out of the box, surprisingly it does not have a proper retail box. It comes with a large travel case which contains all the accessories and cables. I love the way it keeps the things organized. There are a few documentations, one with the nozzle’s color and its effect on sound can be handy. The earpieces are stuffed in the foam. There are 6 pairs of tips inside a transparent case. There are 8 pairs of nozzles and 6 pairs of nozzle filters screwed in couple of aluminum (will elaborate them in the sound section) holders. There are two pair of back plate ports stuffed in the foam just over the earpieces.

The best thing about the package is the cables. If the last gen was excellent with two cables the latest generation comes with three cables. There is a 3.5mm cable, a 2.5mm and a 4.4mm balanced cable. No other brand has ever shipped their earphones with three cables, ever. The 6.5mm adapter, an instruction booklet and cable ties rounds up the looooong list of accessories.


There are a lot of options in this price range. The 600 GBP nearly touches the big boy’s league with fancier build material and designs and a lot of brands are use semi custom type builds but most of them don’t have metal housing. The Mia is one of the rare earphones which use full metal shell and the build quality is excellent. The back plate is held in place with screws and feels very sturdy. Dropping it on the floor will not damage it from outside but it can be a different story inside. What stands out about the Mia is its rear port which makes it an open or closed back earphone without much problem. This feature is not seen with any earphone in this price segment. There is barely any earphone which incorporates metal into semi custom type shells but brands do try to make them a bit curvy and contoured. Mia doesn’t have much of an ergonomical design.

At first glance the Mia doesn’t look much promising with its ergonomics. The design is already quirky and notch to accommodate the screw gives an impression that it might not be very comfortable inside the ear. In reality it really manages to sit inside ear comfortably. The biggest reason is the longer than usual nozzle depth, it really gets deep into the ear canal giving a very secure feel. The earpieces are not heavy and the lower than usual weight help it stay in ear without much problem.


I am a huge sucker for good quality cables and these IEMs with heavy price tags deserve an equally complementing cable, both sound quality wise and aesthetically. A fantastic IEM with bad cable will not leave a very good impression. There are earphones priced at around $700 which ship with run-of-the-mill cables. To my surprise the Mia ships with three beautiful looking cables. The first one is a 3.5mm cable which can be used with most sources and a 2.5mm cable which brings a smile on faces of people who have balanced sources and the 4,4mm balanced cable is the cherry on the top. The 6.5mm adapter gives the flexibility to use the 3.5mm cable with desktop DAC/AMPs.

The Opus Mia has dual core single crystal oxygen free copper braided cables.  There is a generous amount of rubber on the cable which kind of makes the cable a bit stiff, thankfully the braiding is not very tight. It is not the supplest cable but it doesn’t have much memory and doesn’t tangle easily. The Y splitter is minimal in size and the chin slider comes in handy. The cable guides are very supple and doesn’t have any stiffness to them, it is the last thing one needs to worry about.



Suman Sourav Meher

Suman Sourav Meher

My humble audiophile journey started in 2010, when I was in college, where I fell in love with the elements, nuances, and variations of this mesmerizing world. The ability of tiny earphones to recreate amazing sounds made my bad days tolerable and good days better! Now I am a full-time audiophile with a preference for musical tracks, especially vocals and engaging ones. I must admit I am addicted, but not to drugs or alcohol, but to earphones. Come join me as I share my experiences, bad or good, and let’s have some fun!


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