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Ultrasone PRO 900 Headphones

I wholeheartedly recommend the PRO 900 to modern recordists and mixers who need a top-quality set of pro headphones

Perched atop Ultrasone’s high-quality professional headphone line, the new PRO 900 closed-back headphone ($599 list) is a luxurious, comfortable, and well-made pair of studio-grade cans.

Specifications include a 6 Hz to 42 kHz frequency range, 40mm Mylar/titanium driver, 40-ohm impedance, 96 dB maximum SPL, and a weight of 0.65 lbs. The complete PRO 900 package includes a canvas-covered, hardshell case with coiled and straight 10-foot cables terminated with Neutrik connectors, a 1/4-inch to mini-jack adapter, spare ear cup pads, a 20-song reference audio CD compiled and largely recorded under the direction of Ultrasone, and a manual.

Featuring proprietary S-Logic Plus technology — which, in part, requires off-center drivers angled towards the listener’s outer ear — the PRO 900 has a unique sound for headphones that you may, or may not, be used to. However, it is my belief that the S-Logic technology greatly contributes to the PRO 900’s impeccable imaging and fine detail necessary for engineers who use phones for meticulous editing and monitoring.

In direct comparison with high-quality conventional studio monitors, I did hear detail in the PRO 900’s performance that wasn’t apparent in the monitors; for example, in listening to The Beatles’ “I’ve Just Seen A Face,” I distinctly heard a harmony vocal, albeit short and mixed way back, with depth and detail that I had never even noticed before (and I’ve easily listened to the song several hundred times on dozens of sound sources). To my ears, the PRO 900 offers pronounced detail and acoustic presence at comparatively low levels; this quality will surely have you monitoring at lower-thannormal SPL, thus healthier listening habits over time — a notable and beneficial feature indeed.

On the PRO 900, pristinely produced vocal-oriented pop music — with reference material ranging from music by Beyoncé to Big & Rich — was translated with notable “air,” well exposed reverb tails, and an overall “depth of mix.” I wasn’t as trustworthy of the PRO 900 when it came to low-frequency- based reproduction, though. On heavily compressed rock, such as Atreyu’s “Right Side of the Bed,” for instance, low end was rather “woofy.”

If I were making mix decisions on similar material using the PRO 900, I would’ve produced a comparatively anemic mix, albeit possibly more pristine and “deep,” but likely not “commercially competitive” within rock genres anchored by guitars with excessive low end and pronounced “chug.” In other words, I trust the PRO 900 for its abilities in the realms of imaging and detail, yet would approach frequency-based decisions, especially those involving heavily compressed instruments and mix bus audio, with caution, or at least another pair of phones or, ideally, a pair of conventional studio monitors. I did just this and made some great mixes by predominately using the PRO 900 as a monitoring reference (mixes that even remained unchanged when referenced on my trusted studio monitor).

The PRO 900’s $549 street price is at the top of our industry’s pro- or studio-specific headphone range. As such, you’ll initially cringe when handing them to a musician in your studio. (Or, at least, I did.) Luckily, the PRO 900 is a headphone built to take common studio abuse, such as ear-bleed-inducing tracking sessions while perched on the heads of rock drummers, guitarists, and vocalists. The PRO 900 is also physically fit: ready for studio wear and tear and, dare I say, built to be droppable. I’ve yet to use any set of phones that I consider worth buying for studio use that aren’t up to being dropped, yanked, or accidentally kicked across the floor again and again.

In use as musician cans, the PRO 900 will seal well around most ears and heads; thus, you can give them plenty of juice and not suffer much from monitor bleed into your microphones. In my time with the PRO 900, every musician that used it had nothing but good things to say about its sound and feel, nearly to the point of disappointment if I didn’t hand them the sole pair of PRO 900 cans I had during multi-musician tracking sessions.

In summation, I wholeheartedly recommend the PRO 900 to modern recordists and mixers who need a top-quality set of pro headphones and whose work generally ranges anywhere from dynamic classical, jazz, and “lightweight” pop to conservatively compressed rock music. And, while rather pricey, the PRO 900 is an incredible musician’s studio headphone, too. Just be prepared for a band fight if you’re a tracking engineer with only one pair.

Contact: Ultrasone |

Strother Bullins is the Reviews & Features Editor for Pro Audio Review.