ACS Evoke custom in-ear monitor – The power of one.

ACS Evoke custom in-ear monitor featured
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ACS is a company that specializes in producing custom in-ear monitors but you can also buy their models in a universal format. They have over 20 years of experience in the industry and have locations around the globe including Europe, Asia, Australasia, USA and Africa. Today I’ll be looking at their single balanced armature, entry-level model, the ACS Evoke custom in-ear monitor.

The Evoke is available at a starting price of £249.00. You can find more information and pricing at ACS Custom.

This product was provided for the purpose of an honest review. I’m not affiliated with the company and all observations and opinions here are my own.

  • Build quality and comfort
  • Fantastic stock cable
  • Great value
  • Lacks treble presence at times

No. of Drivers 1(wideband)

Build Material 40 Shore, custom fit, medical grade silicone moulds finished with a hard wearing flexible lacquer

Cable Type Detachable ACS IEM Twist Stereo Cable

Standard Cable Length 1.5m

Standard Connector Low profile 3.5mm stereo right angled plug

Frequency Range 20hz-20Khz

Sensitivity @ 1Khz 105.5db

Impedance @ 1Khz 48ohms

Package & accessories

The ACS Evoke arrived in a large, black box with the ACS logo embossed in silver on the front. At the bottom corner is a customized sticker printed with the recipient’s name. Opening the magnetically sealed box reveals a very tidy layout within. On the left side is the documentation, tucked into a little pocket. On the right is the carry case (above) and the ACS Revivo dehumidifier (below).

Let’s run through everything included:

  • ACS Evoke custom in-ear monitor
  • ACS Revivo dehumidifier (including USB charging cable & desiccant
  • IEM zip case
  • 1 x tube of comfort cream
  • 6.35 mm adapter
  • Wax cleaning tool
  • Thank you card
  • Warranty card
  • CIEM Instruction booklet
  • Revivo Instruction booklet

As you can see that’s quite a bundle. First impressions are very positive and overall the package feels premium.

ACS Evoke box
ACS Evoke box open
ACS Evoke unboxing

The included IEM zip case is very good quality. It’s a bit too large for pockets but is perfect to throw in a bag and with this type of IEM, you should really keep it stored well.

ACS Evoke zipper case

ACS Revivo dehumidifier

Description (from the ACS website):

ACS Revivo is a portable rechargeable electronic device designed to remove the harmful moisture and bacteria that can penetrate into any electronic devices worn in the ears.

The special high-speed fan circulates air inside the Revivo to capture moisture via the replaceable silica gel desiccant sachet. Titanium dioxide and UV reactions generate hydroxyl radicals and negative oxygen ions to both sterilise and sanitise the devices.

The Revivo is extremely well built. Its plastic case is thick and robust. After a full charge, it’s good for 30 hours of use. There’s an LED indicator next to the micro USB port which displays a red light while charging. On the top is the power button with an additional LED that lights up blue when the battery is getting low. You can choose different program cycles from 3 to 30 hours. This is a great addition and adds even more value to the bundle.

Build, customization & comfort

ACS’ custom monitors are made from silicone, which is a little less common than the acrylic variant. The benefits of silicone ear moulds are the comfort and superior noise isolation. Therefore silicone is a great choice for musicians and performers but of course, these things can be benefits for music lovers as well.


The silicone moulds are built really nicely. There are no air bubbles or inconsistencies visible anywhere, so you can get a nice, clear view of the inner workings of the monitors. They’re pretty firm shells and feel as though they should be quite durable and robust. There is a single tube leading into the ear, unlike acrylic shells that tend to have 2 or 3.

There are some interesting new technologies present throughout the entire model range. The first is IRIS – Intelligent Resonance iSilicone which ACS says allows very precise acoustic tuning and mimics the warmth of valve amplifiers.

Secondly, SSI – Sound Stage Imaging aims to enhance the soundstage by adopting a wider array than other earphones. Does it work? I’ll cover this more in the sound section below.

ACS Evoke faceplates
ACS Evoke hanging
ACS Evoke side view

I want to talk about the cable for a moment here. ACS’ new (since 2017) twisted cable is one that they developed in-house themselves and it is spectacular. All their new cables are detachable so they’re easy to replace or interchange across all the different models. The cable is thick yet smooth and supple. There’s very little microphonics present and it’s also very resistant to tangling.

There’s a clear plastic Y-split with a matching chin slider. The cable terminates in an L-shaped 3.5 mm plug, complete with good strain relief. This is by far the nicest stock cable I’ve seen supplied with a CIEM to date and I just love it.

ACS Evoke with cable
ACS Evoke plug
ACS Evoke cable

Okay, diving in here so let’s take a look at your options. First of all are the colours. There are 10 colours on the website’s list you can choose from, all of which are translucent. Some examples are translucent champagne, translucent slate grey etc. You can also choose from 3 different cable styles, one of them being 2.5 mm balanced. Lastly, you can opt to get laser text etching, so you could, for example, have your name etched onto the sides.


Like I always say, this will depend on sending in good quality ear impressions to ensure a proper fit, so make sure you follow the guidelines and let your audiologist know the requirements. Unlike acrylic CIEMs, silicone monitors require closed-jaw impressions.

For me, these are extremely comfortable indeed and after some time it’s not difficult to forget that they’re in your ears. There is one drawback to silicone shells, at least for me personally: they are much more difficult and take longer to insert into your ears than acrylic shells. Fortunately, the supplied comfort cream (basically a water-based moisturizer) makes the process a whole lot easier. You don’t need to use the cream but I would strongly recommend you do.

The silicone CIEMs maintain an excellent and consistent seal, even when you’re opening and closing your mouth. Noise isolation is bonkers and surpasses anything I have experienced with acrylic shells. Put these in your ears and they simply shut out the outside world, even before you start playing music.


The ACS Evoke custom in-ear monitor has a smooth sound with a warm tilt. It’s quite mid-forward, with a strong emphasis on the midrange and vocals. Bass plays a big part too and is positioned just behind the rich midrange and adding a solid amount of body to the sound. The sound is rounded out with a smooth but clear treble. All this is provided by a single balanced armature driver and believe me if I wasn’t able to see it through the translucent silicone shells it might be hard to believe.

Just like its name suggests, the Evoke stirs the emotions and gets you involved in the music. I’m singing along to some old favourites as I write this and that’s about as good a sign as you can get.

Gear used for testing

I haven’t had a great deal of experience with single BA IEMs but I’ve heard a few. What immediately made the ACS Evoke stand out from the others I’ve heard was the solid bass. It has a real body to it, nothing like the generally fast but shallow bass I’m used to from a single balanced armature.

The ACS Evoke custom in-ear monitor carries some real authority at its low end and doesn’t sound inhibited in the least. The attack is a little on the slow side, giving bass notes a rounded front edge and imparting that sense of a heavy impact. However, there is still enough texture there to avoid that ‘hitting a pillow with a stick’ effect. Decay, on the other hand, is pretty quick so there’s that typically well-controlled bass that is characteristic of BA drivers.

When it comes to sub-bass this single driver CIEM really delivers. Listening to Nas’ “Take It In Blood” was enough to confirm the Evoke has the goods. It digs deep and extends really well without falling off too early. Also on the cards was a playthrough of “Motive 4 Murder” by Twista & The Speedknot Mobstaz. Fans of old-school hip-hop can be assured that the Evoke will do justice to that classic 808 bass.


Here is where you’ll find the star of the show. The Evoke highlights the midrange, putting it in front of the bass and treble. Vocals are forward, intimate, rich and emotive, while instruments stand out clearly. In the lower mids, you get a nice touch of warmth that blends in nicely with the bass, without any significant bleed. It adds body to male vocals and prevents music from sounding anaemic.

In “To Everness” from Paint the Sky Red, the Evoke faithfully reproduces the guitar notes with accurate tonality and brings them to the forefront, rising above the orchestral strings and bass. It also does a great job with stereo separation here, throwing various instruments at you from both sides while the body of the song stays centred.


Treble is a little bit understated, so there’s no sibilance or harshness but as a result, some of the more subtle details can get lost. Having said that, however, the Evoke still manages to impart a sense of airiness in the music. The quality of the treble is excellent but at times I wished for a bit more in quantity, particularly in high-hats and cymbals.


The Evoke’s soundstage is actually really good. It’s surprising considering the treble can at times come across as a little muted. I’m willing to bet that ACS’ SSI – Sound Stage Imaging is playing a part here and whatever they did it really does work. Not only does it reach fairly wide but there’s plenty of depth too. Vocals sit in front of the listener, still intimate but not in your face. Imaging and instrument positioning are good, so you can easily determine where sounds are coming from.

Sources & compatibility

The ACS Evoke custom in-ear monitor paired well with everything and only showed minute changes in frequency due to the properties of the source. I didn’t hear any hiss or background noise with any of these sources.

Topping DX7

A wide soundstage with forward and intimate vocals. There’s some added energy in the treble giving high frequencies some lift. Midrange is slightly leaner and revealing with less body. Bass and sub-bass have less depth and impact.

Acoustic Research AR-M20

The M20 gives the Evoke lots of depth in the soundstage. It fills out the mid and sub-bass a bit giving more impact and weight. Treble is very similar, maybe a little less than the DX7. The midrange has some more body and fullness. Detail and separation are excellent, bringing a smooth sound and not sacrificing any quality.


Wide soundstage. Detailed midrange with a bit less body but great tonality. Bass unchanged, similar to DX7 levels. Vocals are a little further back and very textured. Clear and airy treble adds to the sense of space and enlargens the soundstage. Very transparent and uncoloured sound.

ACS Evoke print on shells


ACS Evoke vs Custom Art FIBAE 2 (starting at €475)

The FIBAE 2 has a more V-shaped frequency with a similar bass presence but more energy and sparkle in the treble. As a result, its midrange isn’t as forward as the Evoke’s but it does carry a touch more clarity and separation and ACS’s CIEM competes remarkably well with half the driver count and significantly lower cost.

There’s a kind of rawness to the FIBAE 2 that I find rather exciting where the Evoke has a tube-like smoothness that mellows the sound more. Both of these CIEMs share a similar sound signature but the biggest differences are in the treble and the Evoke’s emphasis on vocals. The soundstage of both monitors is very impressive, giving an impression of a 3-dimensional space with the FIBAE 2 pulling slightly ahead in terms of left and right separation.

ACS Evoke comparisons


The ACS Evoke custom in-ear monitor surprised me in a few ways. First of all is the fullness of the sound brought by its single balanced armature driver, particularly in the bass and midrange. Then there’s the quality of the build and that fantastic cable. Finally, the overall value that you get from this entry level CIEM package is what makes it really stand out.

For audiophiles and music lovers, this would be a great starting point if you’re considering going down the CIEM route. Even more so, I would heartily recommend these for musicians or performers. If you have thought about getting custom monitors but hesitated because of the usual inflated prices then the Evoke could be just what you’ve been looking for. It comes with a great bundle, quality of sound that will impress you and most of all great value for money.

Have you taken the plunge with a custom in-ear monitor yet? Let me know in the comments below.

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