Ultrasone Pro 900i Review

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Ultrasone Pro 900i Review

Ultrasone has proven themselves as a trusted world-class headphone brand, due in no small part to the fact they produce quality products that cut across all use types. A model that has exemplified this - as evidenced by its popularity over the last couple of years is the Pro 900i professional use model.

The Pro 900i claims to be ideal for both audio professionals, and audio enthusiasts who are serious about getting the best quality of their listening. So, let’s take a look and see what exactly these have to offer, starting with the box.

What’s in the Box?

The box here is a simple and aesthetically pleasing one that has a nice looking image on the front, as well as a handy list of specs and delivery information on the back.

When you open it, you have just a single compartment that contains your black semi hard carrying case, which is a fairly medium to large size rounded square shape.

Inside the box are the headphones themselves, which fold flat and are kept in place here by some soft material cut outs.

Above this is a bag that features one of your cables. This is an ultra soft single sided cable with 3.5m Neutrik connectors that are threaded so they can screw in. The second cable is underneath a velcro strip strip, and is coiled, with a quarter inch end. 

There is also an instruction manual, and a second pair of quick switch velour earpads.

Design and Fit

The first thing to note on the design front is the headband, which is quite robust in size and fairly thicker than an average size might be. However, this does not make the headphones suffer on the comfort side. The headband is made of a pretty soft artificial leather material with good padding and a balanced weight that makes them sit on the head comfortably. They are also pretty flexible as well as easily extendable, so fitting most people shouldn’t be an issue.

The total weight of the headphones overall comes in at 295 grams.

In terms of build quality here, these are almost entirely plastic, with the exception of the metal plating on the exterior of the housing. This may initially cause some concerns as to durability, but a quick inspection will affirm that all the joints here are solid and move well enough to keep these apprehensions at bay. Even with the material, these never feel cheap or fragile.

The yokes here swivel freely and can be folded in to make these collapse to about half of their normal size for convenient carrying and transportation. 

Even though you may not be able to tell from the box, the earcups here are actually quite large, and extend pretty much from my lower jaw all the way up to almost where my temple is. This is great for a really enveloping quality for the sound, but it’s not the most ideal to me personally because of my glasses. The clamp force is also a factor here, which I would call a medium to moderately strong.  

As for the earpads, they are velour which means they are very nicely soft, and cushiony - but also retain a firmness that keeps them in place and forms a nice seal. This makes for a really good amount of isolation and passive noise cancellation, as the size combined with the material makes a lot of your exterior environment disappear. 

Check out our unboxing and video review as well that you might useful.


Driver Technology

One of the main reasons that Ultrasone can boast such an exacting and clean sound reproduction is the driver

These headphones implement a 40mm titanium plated mylar driver, which is among the most rigid available in any headphone unit. This ensures for high clarity and accuracy.

When talking about the unique characteristics of Ultrasone headphones and the sound they produce, there are two distinct important technologies to factor in.

The first is Ultra Low Emission shielding. Most headphone drivers output a low frequency magnetic field when they convert between acoustic and electric signals. MU metal shielding reduces this emission by up to 98 percent compared to other headphones that do not use this.

The second technology to mention here is Ultrasone’s S Plus technology with natural surround sound. 

S Logic Plus is all about decentralized driver placement. While most headphones feature drivers that are positioned to send sound directly through the ear canal, Ultrasone’s S Logic plus instead places the driver at a different position and angle to bounce soundwaves against the outer layer of the ear at different directions.  This much more accurately mimics the way we hear sound in real life. And provides a much more naturalistic and three dimensional listening experience.

It is also safer for your ears, as there is less direct pressure on your eardrum. This means you can listen at the same volume as another headphone but do significantly less damage to your hearing

You can see how this would be especially valuable for the audience Ultrasone is targeting here, as audio professionals and hifi enthusiasts who are wearing headphones hours a day are certainly going to benefit from this. 


The frequency range put out by the Pro 900i is a very robust  6 hz to 42 khz, to provide a wide palette of detail and sonic information, which makes a lot of sense for a reference focused unit.

It also has an impedance of just 40 ohms, hovering right around the standard range. These will be very easy to drive. Whether you want to loop them into a high powered amp system, or just pop them into your laptop to make a demo - the sound is still going to be excellent.


Speaking of which, let’s now get into that all important sound quality. Firstly, the sound stage. The enveloping nature of the earpad and the large amount of space the ear has inside combines nicely with the S Logic plus technology here to create a nice airy quality.These provide pretty good extension for a closed  back model.

The strength here is the verticality, provided as a result of the significant extension both in the bass and treble frequencies. There is a great height and satisfying depth in tracks ranging across a wide variety of genres and the image is very spacious and roomy in this regard.

Sound Quality

Continuing on naturally from here, the low end is very satisfyingly deep and subby. The size is appropriately big, especially if you’re listening to some thumping hip hop or driving electronic music, but the bass is always reproduced extremely accurately here.

In a track like Hawai by Maluma, the laid back reggaeton beat is suitably chilled and a little subterranean, but still has a lot of weight resonance, and retains the exact right timbre to really make this track play extremely well here. It definitely had me reaching for that replay button here.

If there’s any small level of compromise, it’s in the midrange frequencies here, which are just a little bit recessed. It is still very spacious and continues the great separation and detail that I mentioned before, but bridge from low mids to high feels a little absent here, so there’s a bit of a tilt to the higher end of the mid range. This makes elements like electric guitars have a bit of a thinner quality here than they might elsewhere

In something like Teenagers by My Chemical Romance, the really high gain sound of the huge power chords and palm muted bluesy riffs sound a little overpowering, and big built up choruses here were the only time I ever experienced the image start to restrict ever so slightly.

The high range frequencies have a pretty unique quality to them here, as they are slightly accented and push forward pretty prominently in the mix, noticeably so if you’re listening to some familiar material on here. Treble elements will pop a little more and reveal  some more of their details and nuances, but the extension also keeps this range feeling very smooth despite its power, which is not something a lot of other headphones often achieve. 

It’s definitely a very particular characteristic that may not be ideal for some, especially those who are very used to a specific kind of colorization. There’s also some potential for sibilance depending on how you're driving these and what it is it's you are pumping through, but this was largely a non issue for me. 

Despite any quibbles or things I noted here, I found the sound quality to be really excellent and absolutely up to the high bar Ultrasone sets.

The Big Picture

The Ultrasone Pro 900i is a valuable addition to the company’s line of professional headphones, and is sure to provide value whether you are an engineer looking to add to your collection, or an audiophile who wants to give your music library the listening quality it deserves. 

These will be great for you if want:

  • durable and comfortable design
  • a deep and detailed signature
  • high sound quality with less damage to your hearing

These may not be for you if

  • You want a wider stage than the closed back can provide
  • You are not a fan of the high impact treble frequencies 

Get your Ultrasone Pro 900i headphones at Audio46 today!

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