The “Pro” moniker has become sort of a meme at this point.
Just look at all those phones flaunting “Pro” at the end for the sake of having a larger display, or an extra camera. What’s professional about that? Who knows.
Sennheiser, however, isn’t here to mess around. The IE 40 “Pro” is indeed meant for professional use, in this case: stage monitoring. The whole Pro lineup is actually quite interesting, with a number of innovations made exclusively for them. The upper end IE 400 and IE 500 models are a bit too detached from the budget realm, thus the IE 40 fills that lower-end gap.
So let’s get on with the review.
(Note: the ratings given will be subjective to the price tier. Definitely the expectations from a $15 IEM won’t be the same as a $150 one, and that’s the approach taken while assigning scores. I bought the IEMs with my own funds, still, Disclaimer)
Sources used: LG G6/G7, Questyle QP1R, Yulong DAART Canary, iPhone SE, Cowon Plenue D
Price, while reviewed: 99 euros. Specs can be found on Sennheiser’s website.
Build: The entire IEM shell is made out of plastic (presumably ABS), and while plastic IEMs are a pet-peeve of mine, there is a good reason behind this. These IEMs need to be lightweight, and should put up well with every day abuse. A plastic shell takes care of both as metal would definitely be heavier. In fact, the shells here are quite sturdy and unless you actually step on them I don’t see why they should break apart.
The IEM connectors are the first innovation Sennheiser has made for this new lineup. Their proprietary connector has an MMCX-like shape but it is elongated, resulting in a deeper, more secure fit and far easier cable-swapping. On the downside, the IEMs rotate easily on this new connector, but that’s a small price to pay for the added durability. Regular MMCX connectors get loose after a few months anyway.
As for the more minute details: there’s a vent-hole at the back that releases pressure. The cable itself is pretty sturdy and utilitarian, with ample strain-relief everywhere esp the L-shaped jack.
Now it’s time to highlight my biggest issue with these IEMs — the finish of the shells. The clear shell especially does not look premium at all with numerous molding marks around the driver housing. The black version fares better on that regard, but still looks cheap.
4.5/5
Accessories: Sennheiser didn’t skimp on much in terms of accessories. You get 4 pair of eartips (1 pair of foams included), a soft carrying pouch and a cleaning tool. The eartips are made specifically for these IEMs and they have a very unique “double click-point” mechanism for fitting which allows for both shallow and deep fit. More info can be found here.
Another thing about the eartips that you should be careful about: they have (acoustic?) filters inside them. This is something I have never encountered before in eartips, and kind of caught me off-guard as I lost the foams on one of the eartips while trying to clean them (yeah, I know).
Needless to say, this makes using third-party tips a bit of a challenge as the IE 40 Pros don’t sound optimal with them. Something to take note of if you’re picky about eartips.
Other than that, my two nitpicks regarding the accessories: lack of a hard case and a 6.3mm adapter. The former would have been a better addition than the flimsy pouch Sennheiser has provided, and the latter would befit the “Pro” moniker of these IEMs.
4/5
Comfort: The IE 40 in general has a comfortable fit. It’s lightweight, the tips are of good quality and the IEMs are small enough to fit snugly in your ears and has no hard edges or protrusions to cause discomfort.
However, that memory wire might be a point of contention for some, as I am not a big fan of them myself. They tend to stay in place well once you’ve adjusted them, but it’s something you have to do every time you take them out of your pocket. A minor annoyance, but annoyance nonetheless.
4/5
Now, onto the sound. Sennheiser is using a single 10mm dynamic driver here, unlike the usual hybrid/multi-BA IEMs available at this range, so it should be quite interesting.
Lows: The mid-bass boost is immediately noticeable in the IE 40, and it leads to a mild bass bloom that slightly bleeds into the lower mid-range. The sub-bass is not boosted to the same degree, however, and has a pretty noticeable roll-off around 30Hz. You do hear slight sub-bass rumble, but not to the extent of actual bass-head IEMs.
Bass speed is average with a rather natural attack and decay. The bass is not hyper-fast like the BA drivers, nor does it have the “tightness” of certain dynamic driver IEMs. It does add a nice body to the snare hits, as can be heard on Blackfield’s Once. And the extra mid-bass boost is quite useful in stage/commute scenarios, where the surrounding ambient noise drowns out those particular frequencies so due to that particular boost you can hear the bass notes even in noisy environments. That, however, might be a deal-breaker for those who prefer a lean, fast bass response.
4/5
Mids: Upon first listen in a quiet room, the IE40 Pro’s midrange might seem “recessed” and “distant”. It’s mostly because of the bass boost, however, as the mid-range is not particularly recessed like the “v-shape” bass canons out there that completely ruins midrange tonality.
Sennheiser has gone for a rather unique mid-range tuning in this range. The lower mids are not as scooped as some other models (which usually leads to thinner sounding male vocals and gives a sense of “soundstage width” that is actually messing with the tonality) and there is a very smooth rise up until the 2KHz region. This essentially means that the IE 40 Pro does not focus on male/female vocals specifically and both sound homogeneous. Contrast this to the numerous IEMs out there with a sharp 3KHz peak to gain more female vocal presence (that often leads to shoutiness) and Sennheiser’s focus becomes apparent — they tuned it to have very lifelike vocal representation.
And the vocals indeed are mighty impressive. Damien Rice’s Sleep Don’t Weep has both female and male vocals and showcases this linear mid-range tuning rather well.
However, all is not perfect with the mid-range. The lower-mids sound a bit too full than neutral, so the low-growling vocals in metal tracks tend to sound compressed. Also the upper-mid region could have had 0.5dB or so boost as in stock form, the string instruments lack the initial “attack” or bite, which results in a slightly blunt sounding acoustic guitars, for example. Also, the midrange isn’t exceptionally resolving, so those looking for gobs of micro-details will be disappointed (though in this price-range it’s a bit too much to ask).
All that nitpicking aside — the midrange tuning here is really good in terms of both timbre and tuning and facilitates a laid-back listen.
4.5/5
Treble: Sennheiser has gone for a very safe and smooth treble tuning with a couple dB of boost around the 6–8KHz range. This helps in saving the cymbal hits and crashes from the bass bloom, along with giving some sparkle in the upper regions so that the whole IEM does not sound dark. Also, during stage monitoring, the drummer can use them too and not have ear-fatigue later on.
The treble tonality follows the pattern of the mids: natural decay with a slightly blunted attack. It’s well-suited for extended listens.
The issue lies with the upper treble as I found hint of graininess in hi-hats and ride cymbals. For example, in Lamb of God’s Ruin, from 2:40 min onward, the rather brutal drum line doesn’t sound as resolving as it should with occasional smearing of hi-hats and cymbals. Also, as with the mids, overall micro-detail rendition is on the average to above-average scale at best.
4/5
Soundstage: Width and height is above average, while the depth is just average. It doesn’t sound congested, nor does it sound exceptionally wide. Do note that soundstage perception changes from one ear to the other, so your mileage may vary.
3/5
Imaging: Central imaging and left-right separation is excellent. You don’t get holographic imaging due to the poorer “cardinal” imaging, i.e. you don’t get the sense of top-right/top-left that well and instrument placement is mostly flat. Instrument layering is above-average.
3.5/5
Bang-for-buck: Sound-wise, these hold their ground solidly against the competition, especially given that there is a shortage of stage monitors in the chi-fi realm. The build is solid, so are the accessories for the most part. Sennheiser also backs them with 2 years warranty, and these should hold their value pretty well over the years as Sennheiser does not discount IEMs that heavily over time (unlike the chi-fi competition). Overall, a solid purchase given the price tag.
4.5/5
Source and Amping: Be careful about high output impedance sources as those tend to boost the bass even further, making it uncontrolled. Most sources/phones can run these just fine otherwise as the sensitivity is pretty high.
Select Comparisons
vs Shure SE215: Shure SE215 is (far) inferior in every single facet. Every. Single. One. Case closed.
vs Final E4000: The E4000 costs slightly more than the IE 40 Pro, but shares some similarities: both are single dynamic driver, both has fantastic tonality and timbre and both has a bass-boosted signature. The IE 40 Pro has a heavier bass focus, however. Build quality goes to the E4000, while accessory set is mostly a tie. In terms of comfort, I prefer E4000 personally.
I can’t choose between the mid-range performance here. E4000 is better with string instruments and female vocals on certain tracks, while the IE 40 Pro does male vocals and piano/keyboard better. Treble presence is more noticeable on the IE 40, but the E4000 treble is smoother and doesn’t exhibit the upper-treble graininess of the IE 40. E4000 is much harder to drive.
They are both good options in this price range so you can’t go much wrong with either if you are into that kind of signature.
vs RHA T20i: T20i costs slightly more, but considering the shell type it did feel like a good competitor.
The RHA model wins hands down when it comes to build quality and accessories. IE 40 Pro is more comfortable due to the lighter shell. Tonality and timbre goes to the Sennheiser, as T20i exhibits a metallic “sheen” to its timbre which is more noticeable in vocal-heavy and acoustic tracks.
In terms of bass response, T20i digs deeper with more sub-bass rumble, and has a leaner mid-bass (with the default reference filter). Mid-range tonality goes to IE 40 Pro, and it’s also more forgiving of poorly mastered tracks. T20i shines with well-mastered tracks but will heavily pick out flaws in the recording. Treble is even more extended on the T20i but the upper-treble “zing” can be distracting on certain tracks. IE 40 Pro in contrast has a smoother treble response. T20i outperforms IE 40 Pro when it comes to soundstage/imaging and general technical performance including micro-detail retrieval.
If you are into metal genre/sub-genres or synth-pop/pop, T20i will serve you better with its more v-shaped tuning. For commuting and extended listening sessions across a variety of genres, IE 40 Pro is the easier pick.
Conclusion
Sennheiser has been out of contention in the sub-$100 space for quite a long time. I had my doubts with the new IE Pro series at the start, but the IE 40 Pro was a rather pleasant surprise. The tuning is very mature and definitely meant for professional stage monitoring, it’s comfortable, built well and comes with a great warranty, the cable is more robust than regular mmcx, and the tonality/timbre of these are some of the best under $200.
While neutral-heads and bass-averse ears won’t find ultimate sonic pleasure with the IE 40 Pros, those who listen to a lot of different genres will find a versatile pair of IEMs that is well-suited for using during commute.
It’s a return to form for Sennheiser, and I hope they take the budget scene seriously this time around.
#Recommended
Test tracks (as Tidal playlist): https://tidal.com/browse/playlist/04350ebe-1582-4785-9984-ff050d80d2b7
Test tracks (as YouTube playlist, often updated):
Just look at all those phones flaunting “Pro” at the end for the sake of having a larger display, or an extra camera. What’s professional about that? Who knows.
Sennheiser, however, isn’t here to mess around. The IE 40 “Pro” is indeed meant for professional use, in this case: stage monitoring. The whole Pro lineup is actually quite interesting, with a number of innovations made exclusively for them. The upper end IE 400 and IE 500 models are a bit too detached from the budget realm, thus the IE 40 fills that lower-end gap.
So let’s get on with the review.
(Note: the ratings given will be subjective to the price tier. Definitely the expectations from a $15 IEM won’t be the same as a $150 one, and that’s the approach taken while assigning scores. I bought the IEMs with my own funds, still, Disclaimer)
Sources used: LG G6/G7, Questyle QP1R, Yulong DAART Canary, iPhone SE, Cowon Plenue D
Price, while reviewed: 99 euros. Specs can be found on Sennheiser’s website.
Build: The entire IEM shell is made out of plastic (presumably ABS), and while plastic IEMs are a pet-peeve of mine, there is a good reason behind this. These IEMs need to be lightweight, and should put up well with every day abuse. A plastic shell takes care of both as metal would definitely be heavier. In fact, the shells here are quite sturdy and unless you actually step on them I don’t see why they should break apart.
The IEM connectors are the first innovation Sennheiser has made for this new lineup. Their proprietary connector has an MMCX-like shape but it is elongated, resulting in a deeper, more secure fit and far easier cable-swapping. On the downside, the IEMs rotate easily on this new connector, but that’s a small price to pay for the added durability. Regular MMCX connectors get loose after a few months anyway.
As for the more minute details: there’s a vent-hole at the back that releases pressure. The cable itself is pretty sturdy and utilitarian, with ample strain-relief everywhere esp the L-shaped jack.
Now it’s time to highlight my biggest issue with these IEMs — the finish of the shells. The clear shell especially does not look premium at all with numerous molding marks around the driver housing. The black version fares better on that regard, but still looks cheap.
4.5/5
Accessories: Sennheiser didn’t skimp on much in terms of accessories. You get 4 pair of eartips (1 pair of foams included), a soft carrying pouch and a cleaning tool. The eartips are made specifically for these IEMs and they have a very unique “double click-point” mechanism for fitting which allows for both shallow and deep fit. More info can be found here.
Another thing about the eartips that you should be careful about: they have (acoustic?) filters inside them. This is something I have never encountered before in eartips, and kind of caught me off-guard as I lost the foams on one of the eartips while trying to clean them (yeah, I know).
Needless to say, this makes using third-party tips a bit of a challenge as the IE 40 Pros don’t sound optimal with them. Something to take note of if you’re picky about eartips.
Other than that, my two nitpicks regarding the accessories: lack of a hard case and a 6.3mm adapter. The former would have been a better addition than the flimsy pouch Sennheiser has provided, and the latter would befit the “Pro” moniker of these IEMs.
4/5
Comfort: The IE 40 in general has a comfortable fit. It’s lightweight, the tips are of good quality and the IEMs are small enough to fit snugly in your ears and has no hard edges or protrusions to cause discomfort.
However, that memory wire might be a point of contention for some, as I am not a big fan of them myself. They tend to stay in place well once you’ve adjusted them, but it’s something you have to do every time you take them out of your pocket. A minor annoyance, but annoyance nonetheless.
4/5
Now, onto the sound. Sennheiser is using a single 10mm dynamic driver here, unlike the usual hybrid/multi-BA IEMs available at this range, so it should be quite interesting.
Lows: The mid-bass boost is immediately noticeable in the IE 40, and it leads to a mild bass bloom that slightly bleeds into the lower mid-range. The sub-bass is not boosted to the same degree, however, and has a pretty noticeable roll-off around 30Hz. You do hear slight sub-bass rumble, but not to the extent of actual bass-head IEMs.
Bass speed is average with a rather natural attack and decay. The bass is not hyper-fast like the BA drivers, nor does it have the “tightness” of certain dynamic driver IEMs. It does add a nice body to the snare hits, as can be heard on Blackfield’s Once. And the extra mid-bass boost is quite useful in stage/commute scenarios, where the surrounding ambient noise drowns out those particular frequencies so due to that particular boost you can hear the bass notes even in noisy environments. That, however, might be a deal-breaker for those who prefer a lean, fast bass response.
4/5
Mids: Upon first listen in a quiet room, the IE40 Pro’s midrange might seem “recessed” and “distant”. It’s mostly because of the bass boost, however, as the mid-range is not particularly recessed like the “v-shape” bass canons out there that completely ruins midrange tonality.
Sennheiser has gone for a rather unique mid-range tuning in this range. The lower mids are not as scooped as some other models (which usually leads to thinner sounding male vocals and gives a sense of “soundstage width” that is actually messing with the tonality) and there is a very smooth rise up until the 2KHz region. This essentially means that the IE 40 Pro does not focus on male/female vocals specifically and both sound homogeneous. Contrast this to the numerous IEMs out there with a sharp 3KHz peak to gain more female vocal presence (that often leads to shoutiness) and Sennheiser’s focus becomes apparent — they tuned it to have very lifelike vocal representation.
And the vocals indeed are mighty impressive. Damien Rice’s Sleep Don’t Weep has both female and male vocals and showcases this linear mid-range tuning rather well.
However, all is not perfect with the mid-range. The lower-mids sound a bit too full than neutral, so the low-growling vocals in metal tracks tend to sound compressed. Also the upper-mid region could have had 0.5dB or so boost as in stock form, the string instruments lack the initial “attack” or bite, which results in a slightly blunt sounding acoustic guitars, for example. Also, the midrange isn’t exceptionally resolving, so those looking for gobs of micro-details will be disappointed (though in this price-range it’s a bit too much to ask).
All that nitpicking aside — the midrange tuning here is really good in terms of both timbre and tuning and facilitates a laid-back listen.
4.5/5
Treble: Sennheiser has gone for a very safe and smooth treble tuning with a couple dB of boost around the 6–8KHz range. This helps in saving the cymbal hits and crashes from the bass bloom, along with giving some sparkle in the upper regions so that the whole IEM does not sound dark. Also, during stage monitoring, the drummer can use them too and not have ear-fatigue later on.
The treble tonality follows the pattern of the mids: natural decay with a slightly blunted attack. It’s well-suited for extended listens.
The issue lies with the upper treble as I found hint of graininess in hi-hats and ride cymbals. For example, in Lamb of God’s Ruin, from 2:40 min onward, the rather brutal drum line doesn’t sound as resolving as it should with occasional smearing of hi-hats and cymbals. Also, as with the mids, overall micro-detail rendition is on the average to above-average scale at best.
4/5
Soundstage: Width and height is above average, while the depth is just average. It doesn’t sound congested, nor does it sound exceptionally wide. Do note that soundstage perception changes from one ear to the other, so your mileage may vary.
3/5
Imaging: Central imaging and left-right separation is excellent. You don’t get holographic imaging due to the poorer “cardinal” imaging, i.e. you don’t get the sense of top-right/top-left that well and instrument placement is mostly flat. Instrument layering is above-average.
3.5/5
Bang-for-buck: Sound-wise, these hold their ground solidly against the competition, especially given that there is a shortage of stage monitors in the chi-fi realm. The build is solid, so are the accessories for the most part. Sennheiser also backs them with 2 years warranty, and these should hold their value pretty well over the years as Sennheiser does not discount IEMs that heavily over time (unlike the chi-fi competition). Overall, a solid purchase given the price tag.
4.5/5
Source and Amping: Be careful about high output impedance sources as those tend to boost the bass even further, making it uncontrolled. Most sources/phones can run these just fine otherwise as the sensitivity is pretty high.
Select Comparisons
vs Shure SE215: Shure SE215 is (far) inferior in every single facet. Every. Single. One. Case closed.
vs Final E4000: The E4000 costs slightly more than the IE 40 Pro, but shares some similarities: both are single dynamic driver, both has fantastic tonality and timbre and both has a bass-boosted signature. The IE 40 Pro has a heavier bass focus, however. Build quality goes to the E4000, while accessory set is mostly a tie. In terms of comfort, I prefer E4000 personally.
I can’t choose between the mid-range performance here. E4000 is better with string instruments and female vocals on certain tracks, while the IE 40 Pro does male vocals and piano/keyboard better. Treble presence is more noticeable on the IE 40, but the E4000 treble is smoother and doesn’t exhibit the upper-treble graininess of the IE 40. E4000 is much harder to drive.
They are both good options in this price range so you can’t go much wrong with either if you are into that kind of signature.
vs RHA T20i: T20i costs slightly more, but considering the shell type it did feel like a good competitor.
The RHA model wins hands down when it comes to build quality and accessories. IE 40 Pro is more comfortable due to the lighter shell. Tonality and timbre goes to the Sennheiser, as T20i exhibits a metallic “sheen” to its timbre which is more noticeable in vocal-heavy and acoustic tracks.
In terms of bass response, T20i digs deeper with more sub-bass rumble, and has a leaner mid-bass (with the default reference filter). Mid-range tonality goes to IE 40 Pro, and it’s also more forgiving of poorly mastered tracks. T20i shines with well-mastered tracks but will heavily pick out flaws in the recording. Treble is even more extended on the T20i but the upper-treble “zing” can be distracting on certain tracks. IE 40 Pro in contrast has a smoother treble response. T20i outperforms IE 40 Pro when it comes to soundstage/imaging and general technical performance including micro-detail retrieval.
If you are into metal genre/sub-genres or synth-pop/pop, T20i will serve you better with its more v-shaped tuning. For commuting and extended listening sessions across a variety of genres, IE 40 Pro is the easier pick.
Conclusion
Sennheiser has been out of contention in the sub-$100 space for quite a long time. I had my doubts with the new IE Pro series at the start, but the IE 40 Pro was a rather pleasant surprise. The tuning is very mature and definitely meant for professional stage monitoring, it’s comfortable, built well and comes with a great warranty, the cable is more robust than regular mmcx, and the tonality/timbre of these are some of the best under $200.
While neutral-heads and bass-averse ears won’t find ultimate sonic pleasure with the IE 40 Pros, those who listen to a lot of different genres will find a versatile pair of IEMs that is well-suited for using during commute.
It’s a return to form for Sennheiser, and I hope they take the budget scene seriously this time around.
#Recommended
Test tracks (as Tidal playlist): https://tidal.com/browse/playlist/04350ebe-1582-4785-9984-ff050d80d2b7
Test tracks (as YouTube playlist, often updated):