Review: Sennheiser IE 40 Pro – The Earphones with 0 Harmonic Distortion

Sennheiser IE 40 Pro

Being designed and produced by the skillful audio engineers of Sennheiser, you might not be surprised that on your first try of the Sennheiser IE 40 Pro you’ll be in a state of shock, in a good way, by the bassy sound and emphasized vocals when a song such as Red Hot Chilli Peppers – Otherside, Breaking Benjamin – So Cold, or Seven Nation Army plays.

Now, the edge the IE 40 Pro has, which I also consider it simply amazing, is the sound distortion that is impeccable and clean cut even at high volume. Then when you switch to the Glitch Mob remix of Seven Nation Army the lack of harmonic distortions provide you with a neat sonic reproduction.

With these earphones, the sound quality of your music will never be discredited. The best thing is, they aren’t as expensive as you would imagine. A best invested $100 will guarantee you an incredible, error-free audio experience.


The Sennheiser IE 40 Pro earphones are a modest and practical pair of headphones for casual use, but primarily these are the most affordable in-ear monitors released by Sennheiser. As entry-level monitors, they are highly accessible, and are quite competent for most studio use cases.

Key Features

  • Good and in my opinion very neutral sound
  • Large frequency spectrum range
  • Valuable processing
  • Very good price / performance ratio

Sennheiser IE 40 Pro Review

The transparently designed studio in-ear headphones have a nice feature that makes them very adaptable, and that the proprietary cable which can be mounted and disconnected with ease. The easily detachable cable ends with a mini 3.5 mm plug-in connector. It does feel a bit thin at touch and also when looking at it, but besides that, it shows no sign of brittleness, it’s somewhat flexible and durable. The earphones are transparent and you can look inside of them, and because of that they possess a distinctive, exquisite and clear look that I am delighted about. I’m fairly pleased by their look, but also by their sound performance although I haven’t gotten into that topic yet.

The IE 40 Pro build quality seems to be rather average and nothing spectacular to it, I’m convinced though that as long as the main pieces won’t break you’ll be fine since the cable is replaceable and you can order a new one from Sennheiser for nearly $30.



IE 40 Pro​

Recording and Mixing

3 Pairs of foam tips, Foam Adapter, Soft pouch, Cleaning tool, Proprietary cable

Onto the sound quality, this is the area where the vast majority of earphones would suffer, especially in the bass region as a consequence of lack of air, but at first listen I can undoubtedly say the bass makes its way impressively with a warm signature, voluminous and lightly emphasized. The bass is the frequency that impressed me the most, I dare say it’s impactful and energetic and so it holds a tremendous sound presence from the foundation of deep-bass to the very opening of mids. It does decay bit by bit on its way towards the 1 kHz mark, but on its entirety does not lack personality.

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The “V” signature of the sonic spectrum is the most suitable description this frequency configuration could have and the mids appear to be shyer than the rest of the spectrum whereas the bass and the treble are well ventilated, wide and ascended. The vocals stay a bit behind as opposed to the other frequencies; they don’t situate into the limelight as much as, but we’re talking here about a small range, more precisely: 300 Hz – 1 kHz.

I know that the highlights in the midrange and treble might be crucial for doing its job correctly as studio earphones, but the IE 40 Pro is merely Sennheiser’s entry-level in-ear monitors which costs a tad less than a whole lot of other professional studio headphones. Moreover, as professional monitoring earphones, they provide for you with the benefit of relatively low sensitivity (94 dB SPL). While this might not turn heads on when specified, their convenience coupled with a neat audio configuration only leaves with one hindrance: a few slightly more rough frequencies. Other than that, the Sennheiser IE 40 Pro and still flatters me and gets my recommendation,


  • Exemplary sound distortion
  • Sharp and detailed audio reproduction
  • Enhanced treble extension and deep bass


  • Colored high-mids and treble
  • Build seems average


The pronounced bass, the upper side of mids and treble might not drive the smoothest and most analytical sound signature, but could easily be configured to improve their efficiency in monitoring. Ultimately, if this is not the case for you, and don’t require a pair of earphones for studio monitoring, you’ll love the dynamism of these natural fun-sounding earphones on an everyday basis.

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