Headphones and Earphones

Ultrasone Pro 900 Over-the-Ear Headphones

Ultrasone Pro 900 Headphones


Recently, I have started to put more of a focus on using headphones in my office instead of speakers. I enjoy listening to music while working, but my cubicle neighbors don't necessarily appreciate the same type of music that I prefer. When a pair of  Ultrasone Pro 900 headphones became available for review, I obtained them to see how they would work in my setup and how they compare to my current reference headphones, the AKG K701's.


  • Design: Over-the-Ear Headphones
  • MFR: 6 Hz - 42 kHz
  • Drivers: 40mm Mylar/Titanium
  • Impedance: 40 Ohms
  • Maximum Loudness: 96 dB
  • Weight: 10.4 Ounces without Cable
  • Cable Length: 3 Meters
  • MSRP: $599 USA
  • Ultrasone

Design and Setup

The Pro 900’s come packaged in a very nice case that keeps everything secure

Ultrasone Pro 900 Headphones

and makes it easy to safely pack them with you on a trip. Inside the case you’ll find the Pro 900’s, two sets of earpieces (silver and black in color, though identical in performance), two cables (coiled and straight, 3m each), and the owner’s manual with a demonstration CD.

Ultrasone Pro 900 Headphones

Both of the cables are terminated with a high quality Neutrik ¼” stereo headphone jack and a ¼” to 1/8” (3.5mm) adapter is included in the package. The Pro 900’s feature a removable cable which will make it easy to replace if a connection starts to go bad (a constant issue I have with headphones), or if you wanted to get an aftermarket cable with a 1/8” connector so you could avoid using an adapter.

Ultrasone Pro 900 Headphones

The Pro 900’s are a relatively large, over-ear headphone that offers plenty of padding and a very comfortable fit in daily use. (Fig 5)The head-strap has plenty of padding so that I didn’t notice any pressure at all on the top of my head, and the ear pads provided plenty of cushioning, as well as a reasonable amount of isolation. While larger than anyone would probably want for portable listening, packed inside of their case I could throw them into my laptop bag for carrying between work and home, or for listening during a cross-country flight.

Ultrasone Pro 900 Headphones

In Use

The vast majority of my listening was done using either a NuForce Icon or an emu 0404 USB as my headphone amp, and CD’s ripped to FLAC as a source and with Grado SR60’s and AKG K701’s for comparison. The first thing that I will mention is that the Pro 900’s did a great job of not leaking any sound, and providing a decent amount of isolation from outside noise. No matter how loud I would turn up the amps, no one was able to tell what I was listening to or how loud it was, a large difference from the AKG’s where their open nature doesn’t work as well with a cubicle neighbor.

Massive Attack

One thing that the Pro 900’s were able to provide in abundance was a lot of clean, clear bass. Listening to old favorites such as “Teardrop” or “Angel” from Massive Attack (Mezzanine), the opening beats hit in a way that I hadn’t heard from headphones before. The bass was clear and precise, loud, but not muddled or bloated. Moving onto other music that I remembered for its bass, I listened to “The Downward Spiral” from Nine Inch Nails all the way through.

The Downward Spiral

In addition to hearing the bass with better definition than before, I was able to clearly hear the distortion in instruments that I had not heard before on “Piggy”. Little details that were there before in the music were now more apparent than anytime I had listened on speakers. The bass offered was far louder and more present than the bass being offered by my AKG’s on the same tracks.

In Rainbows

I moved onto what has become my favorite track of any album recently, “Reckoner” from Radiohead’s “In Rainbows”. The cymbal hits that open the track had great snap to them, and seemed to float in the air. As more instruments came into play and Thom Yorke’s vocals filled in, the music didn’t become messy but rendered all of the instruments very distinctly. After the track finished I listened again, just enjoying how wonderful the music sounded through the Pro 900’s.

The Piano

The weakest area for the Pro 900’s when compared to my AKG’s came in the area of the soundstage. Listening to the score for “The Piano” from Michael Nyman really brought the differences in the headphones to the front. Whereas on the AKG’s I could hear a piano and it sounded truly like a piano being played in a large, open room; when I listened to the same passage on the Pro 900’s it sounded more like a recording of a piano in a small, confined space. The AKG’s were just able to render a much larger, more open soundstage in comparison to the Pro 900’s.

However, the bass offered by the Pro 900’s was clearly louder and more present than on the AKG’s when using the same headphone amplifiers for each.

Norah Jones

Listening to Norah Jones’s first album, “Come Away With Me”, the Ultrasone’s really brought the bass on the track to the foreground, but sometimes would seem to overpower the rest of the instruments or vocals on the track. Listening to “Feelin’ The Same Way”, there is an electric guitar that comes through the left ear very distinctly. With the Ultrasone’s this guitar had far more energy behind it than I heard through my AKG’s. However, with the AKG’s I could better hear the string resonating after it was plucked. I didn’t get the full force of the initial note, but I heard more of the details in the music afterwards.

Though not as likely to be used for a source as a dedicated headphone amp, I did test out the Pro 900’s with a laptop’s headphone output, and the output of my iPhone. Both of them were able to drive them to reasonable listening levels, though the sound became a bit more compressed and muddied than when driven by a dedicated amplifier. They certainly offered a better experience than a cheap pair of headphones would, but adding a portable headphone amp for either of these devices would be recommended, if not necessary, if they were going to be your primary source for listening.


Ultrasone Pro 900 Headphones

The Ultrasone Pro 900’s worked very well in my office arrangement. They offered clear, tight bass and were considerably easier to drive than my AKG’s, which makes them better for systems that don’t have a dedicated headphone amplifier (the headphone jacks on mass market receivers don't have a lot of output volume). They also did a superb job of rejecting ambient noise. The only area that they fell far short of the AKG’s was in the size of the soundstage, but given the open ear design of the AKG’s and the closed ear design of the Pro 900’s, that was to be expected.

For consumers who have musical tastes that include a lot of bass-heavy music, they should definitely audition the Ultrasone Pro 900’s. Sometimes I really missed that strong bass when I changed to a different set of headphones, but then I would hear other details in the music that I thought the Ultrasone’s might be obscuring compared to the AKG’s. It just goes to show you that no single set of headphones has everything.