Westone Audio MACH 40


500+ Head-Fier
Westone Mach 40 Smooth & Resolving
Pros: -Extremely balanced sound
-Fantastic Build
-Very ergonomic, fantastic fit
-Fantastic BA Bass
-Fast transient response
-Imaging is nice
-Extremely good resolution
-Pelican protective case
Cons: -Price
-A bit too toned down for some
-Not for Treble Heads
-Not for Bass Heads
-Hard to drive
-Smaller staging

Westone Mach 40 ($599)
Full Review: https://www.mobileaudiophile.com/westone-mach-40-review/

I just finished reviewing the Westone Mach 30 and so this is a very easy transition to my next endeavor… the Westone Mach 40. I did a complete 180 from where I started with this set as well as the 30. From “Blah” to “Wow”.

I want to first thank Zachik of Westone Audio for including myself as well as our website mobileaudiophile.com in the USA tour of the Westone Mach 30 and 40. As always this will not alter my opinion nor sway my views. I was very happy that Westone chose me to be a part of their tour and would do everyone a disservice to cater or hype anything not worthy of it. Plus, my integrity is of the utmost importance to me.

Westone has joined forces with Etymotic to create the Mach Series. Both are storied companies with a reputation for creating specifically tuned in ear monitors for both the stage as well as at home recreational listening. The Mach Series was a venture to bring a different tuning perspective into each of their iems from the Mach 10 through the Mach 80.

Truthfully, the last Westone iem I’ve had in my ears was around 8-10 years ago and I cannot remember what it was. I own the Etymotic Er2se and do enjoy how they sound. However, for the most part I have spent the majority of my listening life in the Chi Fi world. Before that I leached onto major brands that produce mass market appeal audio gear. Ugh. I suppose we all start somewhere.

One more tidbit. I only had the opportunity to audition the Mach 30 & 40 for 10 days in total. This left 5 days each. Some may think this is enough time but for me it falls way under what I normally put into a review. Most take me at the very least weeks to even utter a sentence. Still, it is enough time to draw some good conclusions. With that out of the way… the Mach 40 everyone.


Gear Used

Zooaux Dongle Dac

IFi Go Blu

Fiio KA3

Ibasso DX240 w/ Amp8 MK2

Left to right: IFi Go Blu / Ibasso DX240 w/Amp8 MK2 / FIIO KA3

FullReview: https://www.mobileaudiophile.com/westone-mach-40-review/

Packaging / Accessories

The Mach 40 comes in a rectangular box with a stylish graphic. Actually, it is a box within a sleeve. A very tight sleeve I should add. Anyways, the packaging is nice and indicative of an almost $600 iem.

The package contains ten tips in total. Five foam tips and five silicone tips. A cleaning tool to scrape the ear-junk out of the tiny front nozzles. Also, a small cloth drawstring bag, colored black-on-gray. The bag is a nice addition that I would actually use.

Another great addition is the Pelican style hard case which is rather large. Much larger than the small Mach 30 case. Actually, this case is roughly the same as a Pelican 1040 case. You will see in the pics below. It is a black and clear case that seals watertight and gives plenty of room for anything you’d like to take with you. Truthfully, I love this case. I could easily fit a Dap and Dongle with a set or two of iems and I’d be comfortable knowing they were perfectly safe. Shove it in my backpack and off I go.

The last and final accessory is the cable. A .75-ohm thin and lightweight cable created by Linum named “Estron Superbax“. This Estron Superbax cable is pretty thin and lightweight, and I can confidently say that it also feels very durable. The Super Bax ends in a right angle 3.5 SE termination. Connecting to the actual iems is what Linum refers to as a “T2 connector”. T2 connector is an Linum product trademark. The T2 connector is almost a type of mmcx I would say. Much easier to attach and detach. The cable has a quad twisted design with 168 strands of Silver-Plated Copper.

The Superbax cable is quite a bit thicker than the "Bax" cable that comes with the Mach 30 (Estron Bax). The Superbax cable feels like you are wearing nothing when attached to the Mach 40. I believe the cable alone is $149 usd if you were to purchase it separately. Westone promises much better signal transfer and zero microphonics. At least the latter I can confidently testify about.

In truth the Superbax isn’t the best looking aesthetically. It probably isn’t the most handsome of cables but the lightweight nature of it truly is nice. There is a real good feel to it. A certain premium heft and rigidity yet such a feather light design. The Superbax is advertised having a much greater tensile strength then most cables. The T2 connectors are such a great touch as well. I would love to see this connector make it to the mainstream and see many more iem makers adapting the design. Trust me… you’ll like it.

Westone Mach 40 packaging
Westone eartips
Linum Estron Superbax
Westone Mach 40 Pelican style case


Real quick, I will quite literally copy and paste my report of the Mach 30 here as the two are identical in build and look. Obviously, a name change will occur. Please forgive my laziness but if you had these in your hands…you’d do the same.

Hard plastic was the material of choice to use in the molding process. The Mach 40 has a premium and slick look, also a somewhat minimalist and executive look as well. The plastic used is hard and durable without any blemishes. These simply feel premium to in the ear.

Not only do they feel premium but also have a premium fitment. Westone really got the comfort level right here. The 40 get lost in the ear and nestle perfectly in place. All the rest of the Mach Series is built in an identicle manner. They all have metal faceplates bearing the company name as well as the respective name of each iem and the Westone logo. They all share the same two-toned dark gray housing and light gray Faceplate. Truthfully I can’t really tell much of a difference between them all by shell design alone.

I can tell you right away that the Mach 40 is one of thee most comfortable iems I’ve ever worn. The Mach 40 sits perfectly inside my ears with zero irritation or fatigue. The 40 are very lightweight. Couple that with how light the cable is, it feels like you aren’t wearing anything. This set will likely accomadate any ear type. The 40 also seem to attenuate the outside noise to a better degree than most iems as well. The provided tips are longer than average tips as they insert quite a bit deeper than most. Much like my Shure Se215 and my Er2se, these rely on deep insertion with the very narrow nozzle (pictured below) This is good on a few fronts but as far as noise canceling I’d say this is very helpful.

The Mach 40 employs four exclusive proprietary Balanced Armature Drivers which work in tandem with a 3-way passive crossover. Each of the BA’s takes on a chunk of the frequency. There are two BA’s for the low end, a single BA for the Mids and a single BA for the Highs. Each iem in the Mach lineup is named according to how many drivers they each have. For instance the Mach 10 has “1”, Mach 30 has “3” and so on to the most expensive of the Mach Series iems which is the Mach 80.

Notice the thin nozzles

Sound Impressions
The Mach 40 offers an extremely balanced replay. Truthfully no one area stands above any other area of the frequency. There is a very warm and very smooth sound. Honestly this set is one of the more organic and flatter sounding iems that I’ve had the pleasure of listening to. I simply don’t normally reach for this type of tuning so please forgive me.

The bass is deep and textured. For an all BA set I am very much impressed. The mids stay on that linear path along with the rest of the spectrum. The highs do have a roll-off up top and aren’t the most extended which lends way to the warmer sound. All in all, I hear an extremely laid-back sound to my music. Nothing harsh or fatiguing at all coming from the Mach 40. This is a very Monitor like experience with more of a reference and natural sound compared to most iems out there.



With an Impedance of 30 ohms and a sensitivity of only 100 dBs at 1khz it is safe to say that the Mach 40 needs some extra driving power in my opinion.

Trying a lower powered source like the Zooaux Dongle Dac was a short-lived venture. I could get the Mach 40 to a decent listening volume, but dynamics were all but gone. This device just doesn’t cut it…moving on.

Using something like the IFI Go Blu I also got to volume pretty well with decent dynamics however the stage was a bit more closed in. Maybe resolution suffered a bit but nothing crazy noticeable. Moving onto the Fiio KA3 I did hear a slight bit more clarity and the offset of the more neutral ESS Dac inside did seem to pair better for me. Still, I was able to drive this set just fine, yet I did have to bump up the volume considerably more from many of my iems. Around 70/100. There was some congestion occurring with these first couple devices.

Attaching the Mach 40 to the Ibasso DX240 w/ Amp8 Mk2 on High Gain these things came to life. That’s much better. Dynamics increased as well as transparency and stage width. No more congestion at all. The whole of the replay seemed to get shot up with audio steroids. Basically, give the Mach 40 some juice people.

Westone Mach 40 with the Linum Estron Superbax Cable


The Mach 30 left me impressed with its bass, considering it was a single BA taking control there. Westone chose to add one more BA for the lower region in the Mach 40 and I can hear the difference. It took me listening to “Blue Laces 2” by Nipsey Hussle to hear just how dynamic a natural and more flat replay can sound. There is a depth to the double bassline in this song after the bass drops in which I heard good layering and texture. The Bass never encroached on Nipsey’s voice, and the surrounding melody was effortless for the Mach 40 to display.

The bass here is hard hitting in a very quick and authoritative way. Keep in mind these are not Dynamic Drivers so temper your expectations. I will say, the Mach 40 comes so very close to that sound. The sub-bass has a natural, deep, and guttural haptic vibration that has a good texture to it. Listening to “Pristina” by Faith No More it is obvious how well done this set is in the lowest area. I hear a very tight reverb and focused presentation. Decay is rather quick while the attack is clean and pronounced. I don’t hear any roll-off at all in the sub-bass. These extend in a linear fashion from the sub-bass to the mid-bass.

The mid-bass is just the same as the sub-bass in terms of attack. Now it could be me just hearing things, but it sounds like the mid-bass has just the slightest bit slower decay. It gives a certain presence to the atmosphere in songs which require it. The tonality is warm just like the rest of the spectrum as well.

These differ from the majority of all BA iems. There is nothing pillow-like or hollow about the bass either. Nothing plastic to this bass. The mid bass has a clean-edged roundness to it. Songs like “Marmalade” by Macklemore have a sonorous and boomy bass drop that comes and goes so nicely. The bass alone is worth the $100 upgrade from the Mach 30. Listening to “Better” by Khalid there is a bass drop at precisely 30 seconds in and there is such a satisfying pay off for the waiting.

To sum up the bass. These do the low end nicely. The low end does have an element of fun with enough gusto while remaining very close to neutral and without added coloration. I gotta give props to Westone. Both of the Drivers down low do their job, and the proof is in my library of music and the satisfaction I got. I have obviously heard better but in all honesty, I don’t think I’ve heard better BA bass before. Of course, I also haven’t heard all of the BA sets out there. So, for now…the Westone Mach 40 are sitting on the all BA bass throne…alone. Please excuse my limited access to all BA iems.



The midrange has the same story as far as neutrality is concerned. From the low mids through to the upper mids it is a mostly flatter trajectory, for the most part. I hear a very unprocessed and refined sound which has balance as a mainstay. A warmth covers the entire replay just like a veil, yet somehow clarity is not reduced. I hear absolute precision with clean dynamics. Smooth and even, soft and easy, clean and resolute are some words to describe what I hear.

Lower mids present male vocals as hefty with a nice decay and impact. Velvety is the common theme that ties this set together and the lower mids is no exception. There is no serious recession at all from male vocals as they sit relatively uniform with everything else. The sound has an almost boxed in like effect which I wrote about in the Mach 30 review as well. I did say almost. I’d simply say that it is a different take on male vocals. I have already reviewed the Mach 30 and by the time I began the Mach 40 review my brain had already adapted and I have found male vocals to be quite nice. Again, these are not the best if you are looking for a more V-shaped or Harmanish sound. If balanced / flat is your jam, then this set will do just fine.

Timbre of instruments here seem to veer truer and dare I say…natural. Whatever that means? I’d say they aren’t colored at all. Warmth coats this area like a blanket. Since there is no real spike in the upper regions of the mix there isn’t that brightness to offset the rest. That said, Instruments play nicely with room to breathe in this warmer climate. Like I said, timbre sounds very nice with good separation and positioning.

Female vocals have very nice articulation and nice weight to vocal notes. There is a lack of shimmer though. Females are forward enough yet without the sparkles that I have become accustomed to. Some would probably describe them as lackluster or even dull or blunted. This isn’t my favorite area of this set. I can say for sure that if a fatigue free listen is what you are after then this is the set. The Mach 40 were created for long listening as comfort is a constant.

If you crave that more pronounced levity of a female voice than I’m afraid this is not the set for you. To be fair I don’t think that is what Westone was going for. Westone created a monitor-like sound which stays true all the way out. For this purpose, they have succeeded.



There most certainly is a roll-off present somewhere around the mid-treble area with a lack of volume in the presence region. Again, this is a very flat and reference sound. The treble area is non-offensive and without any spikes to create an unnatural effect. There is a warm extension though which extends through the treble area so as to not leave out stuff like cymbals. They come across pretty natural to the ear. Nothing even remotely splashy, but instead they have a warm tinge to them, just like the Mach 30. The treble is in complete control the whole way through.

I must confess I typically like a more energetic treble region, like a shimmer to offset the veil. I hear a definite lack of a presence region. The resolving nature of the Mach 40’s treble isn’t lost, however. There still exists another small spike in the Mid-treble to at least keep the linear and balanced approach. To be honest, somehow by day 2 with these I was more than happy with the Treble region.

The treble has good body with a thicker note weight. Dynamics all the way out do have a good and warm energy and kind of counter the normal mass market sets that are out there. The Mach 40 isn’t without dynamics, but they don’t really have that glistening twinkle which adds that last cherry on the top. I suppose many would be left in wanting. Just as easy I could see this set being close to an end-game set for some as well. Really this is a well in control and very transparent representation of the Highs.


Soundstage / Imaging/ Details

The stage of the Mach 40 is a bit more closed in. I don’t hear any “big room” type sound. More like a small gathering. Even so this has an intimate and well scaled sound. There is okay depth with the Mach 40 to my ears. Width is only average at best as well as height. I don’t see this as a glaring con though. Part of the charm of this set is the warm and close-knit type replay while remaining resolute under a relaxing veil.

Imaging is good here. Everything has a defined roll and does so with good enough separation. Voices have their center placement for most of my music depending on the type of recording. Strings and horns all sound distinct. No doubt there is a precision edge to every sound, which helps to discern placement.

This is a velvet and rich sound as nothing is elevated in such a way to illuminate tiny details to the surface with psycho-acoustic trickery. Instead, this is a set which thrives on only delivering whatever was meant within a recording. The details which do arise are naturally occurring and aren’t forced in any way. They will not win the most detailed award however they do fine in details. They will not win the or most technical award either, but this is most certainly a technically adept set. I promise nothing is withheld either. It’s simply the nature of the sound. Smooth doesn’t always cater to tight edges and micro minutiae or the intricate little complexities of a live recording for example. Truthfully it also doesn’t have to.

Left to right: Westone Mach 40 / Westone Mach 30

Left to right: Westone Mach 40 / Westone Mach 30


Westone Mach 30 ($399):

This will be rather short. Truthfully, I was going to leave this out, but I figured… why not.

There are some areas where the less expensive Mach 30 does differ from its more expensive sibling. First would be stage size. The 30 have a slightly wider stage with a bit more height. Second, the 30 has more energy up top giving its replay a bit more levity and air. Trust me, not by much. The 30 is also not as warm and has in my opinion a slightly more natural sound. Maybe a titch more open sounding too.

The 40 sounds more engaging everywhere else. For example, the bass region is more impactful with tighter edges and more depth and layering to the sound. The more expensive older brother has a hair better resolution and imaging as well. The stage seems to not become as congested in complicated tracks. Lastly note weight is thicker with more weight to vocals & instruments which kind of adds to the unique atmosphere. Please keep in mind that none of what I listed are really Cons but really just differences. Other than maybe resolution and imaging of course. Preferences do come into play here during comparisons and this comparison is what fits me.

I will also add that the 30 is quite a bit easier to drive than the 40. However, both sets do so very well when extra juice is given. Amping is a necessity for the full shebang with these two.

Both sets are exactly as comfortable as each other and both are meant for a more easy and smooth listening session. Both teeter warm of neutral and both attenuate the outside world nicely.



To finish this review, I would once again like to thank Westone, and Zachik in particular, for giving myself and mobileaudiophile.com a chance to honestly review their new line of iems.

I really can respect a company that delivers what they say they are delivering. The many promotionals that I saw proclaimed that the Mach 40 was going to be a very balanced and smooth listen. Nailed it! They said this was meant for long listening sessions as well… again they fulfilled this promise. Westone said that these would excel in comfort due to the ergonomic design and I would say they are perfectly right. They said that these are meant for both casual listening and for more professional purposes as well.

In my 30 review I said, “What Westone did well is get the intangibles spot on right. The timbre they were after, the smoothness, tonality and the perfectly comfortable fit. I picture a team of talented people going through countless hours of revisions trying to succeed in the vision of what the “Mach Series” was supposed to look like and sound like.” I stand by those words here as well.

Please don’t get me wrong, this sound will not be for everyone. Especially since the price they are asking is getting up there. Truthfully this sound is not typically my favorite. Yet I can appreciate it for what it is and actually really enjoy what they have to offer. Once my brain adapts anyways. Like I said earlier, I absolutely enjoyed the time I had with these. I really try to review an audio device for what it is, rather than what I want it to be, or for how it fits in my particular taste. My taste is not everyone else’s. This is where getting the intangibles right and the technical stuff right is so important. No doubt there is a premium nature to the Mach Series through and through.

If a warmer and more resolute, balanced, and more easy sound is what you are after then you should at least consider this set. There are many competitors in this price point which absolutely excel and truthfully many more which would likely appeal to the masses. I say that to implore you to explore other reviews of this set, as well as other iems in the price point, and to read or listen to other opinions. Not everyone will have the same view as me. I am simply one man with a love for audio and an opinion amongst a giant sea of iems and other reviewers. Thank you so very much for reading and I do hope this helps even a little bit with your purchase. Take care everyone.
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You could say that. It's an acquired taste. If you are used to a more lively top end... You prob won't dig these
very nicely written review Chris. keep it up
Means alot man, thank you