
What is it?
Ollo Audio made serious waves with its initial S4 headphones, taking on existing players such as Sennheiser, Audeze, Beyerdynamic and Slate Audio. It also developed designs in closed-back (S4R), open-back (S4M) and immersive mixing versions (S5X). But now it’s all change, as both the S4 and S5 open-back designs have been replaced by the new open-back X1.
Much like its predecessors, the X1 are hand-crafted studio headphones designed for professional music users rather than the wider hi-fi market. They are manufactured in small runs by Ollo in its Slovenian base, and can be pre-ordered direct from Ollo Audio or bought via selected resellers. They come with a five-year limited warranty and a handy 90-day money-back guarantee.
The X1 sports a bold retro look that features real walnut ear cups coupled with deep over-ear pads. The ear cups are fully rotatable and have slotted back plates with an X pattern and Ollo branding. They are joined together by a springy steel band with an attached headband, and audio connects to both ear cups via a 2m colour-coded Y cable. The headphones come in a stylish zip-up hard case. It’s worth saying that the headphones are designed so users can replace parts easily, and all spares right down to drivers, back plates and sockets, are available to buy direct from Ollo. That said, any major repairs should be referred to Ollo as they may void your warranty.
The X1 can be used ‘as is’ straight out of the box. However, each individual pair is tested and calibrated, providing the registered owner with their own calibration data file. This is designed for use inside USC II (AU, VST, VST3, AAX, Standalone), a software package designed in partnership with developers dSoniq and based on its Realphones correction software.

Performance
The X1 is an over-ear design with a 58mm inner diameter on the ear pads. Couple this with the walnut ear cups and you do have quite bulky headphones. At 390 grams, they are also on the heavier side, although they are still lighter than a number of competing designs. Even so, they are very comfortable and this is down to both the soft ear pads and also the headband, which is elasticated and therefore stretches to accommodate your head size.
As mentioned, you can use the X1 without any form of adjustment and this is how we started our listening tests. The overall sound is reasonably neutral with some subtle air on the higher frequencies. The low-mid and lower frequencies feel reasonably full, but as you would expect for a mixing design, the highs and lows are not over-hyped. What’s more, although they’re an open-back and over-ear design, the snug ear pads still provide some passive isolation.



The USC II software, downloadable from dSoniq, is for both calibration and emulation, and can be used either as a plugin on your DAW output or as a standalone app, dovetailing with your system audio device. Once you’ve imported your own headphone calibration (XPS) file, you can apply the calibration (0 to 100%) to taste, and also choose from a number of emulations, once again setting an amount (0 to 100%). We found the impact of the calibration reassuringly subtle, marginally tweaking the low mids and mid-range.
There are emulations for both headphones (Flat, Spatial, Harman) and listening spaces (Studio, Car, Club), and the Spatial option is designed for immersive users. Further handy features include soloing of just the mono or stereo signal components and overall EQ tilt. Meanwhile, the XPS file format is easy to open in a text editor, which means you can tweak it yourself or replicate the enclosed EQ settings in other headphone calibration systems.
Verdict
Overall, the X1 are excellent headphones that more than meets Ollo Audio’s own remit focused on comfort, sound, repairability and value. They may not be the most slimline mixing headphones available, but they are Ollo’s best offering to date, and we think worthy of full marks.
Hands-on demos
OLLO Audio
Alternatives
Specifications
Price |
£386 pre-order |
Design |
Open-back over-ear dynamic |
Driver |
50mm with composite Pu+PET membrane |
Transducer magnet |
Neodymium |
Impedance |
32 Ohm |
Frequency Response |
5Hz to 22kHz sweep ⅓ octave p-p range 9.8 dBSPL +/-1dB |
Sensitivity |
101 dBSPL @ 1kHz at 1V RMS |
THD |
<0.05% @ 94dB @ 1kHz |
Connection |
Detachable 2m split Y cable 2.5mm to 3.5mm TRS jack with 6.3mm adapter |
Ear pads |
Acoustic foam with artificial leather and velour |
Ear cups |
American walnut |
Included extras |
Hard carry case, 3m detachable cable, USC II software |
Weight |
390g |
Contact |