OLLO Audio X1 1.0 2024

I used the OLLO Audio S5X 1.1 for a number of mixing and Atmos-check sessions to see how well a calibrated open-back headphone could replace, or at least reliably supplement, monitors in an untreated room. My focus was on translation - how decisions I made on these cans mapped to speakers and stem-playbacks - while also checking comfort and the practicalities of the USC calibration workflow.

First Impressions

The S5X arrives with a solid, premium feel - real walnut outer cups, a stainless spring-steel headband and a dense, replaceable earpad feel that immediately communicates durability. Out of the box I noticed a neutral tone and a roomy, open presentation that felt less colored than many other open-back reference cans I've used; there was a clear intention toward translation rather than flattering tonal shaping. The detachable braided cable and the ball-locking 2.5mm connectors are reassuringly robust, and the included USC calibration claim made me eager to test whether the unit-specific correction really delivered tighter matching to a flat target.

Design & Features

The S5X is unmistakably built to be serviced and maintained - every part that typically wears out is user-replaceable, including earpads, headband strap, backplates and even the speakers themselves. The headphones use 50mm PET drivers with a two-layer coil and neodymium magnets, mounted at an angle in wooden cups to favour a natural radiation pattern and spatial rendering. OLLO bundles a USC (Unit Specific Calibration) system - a plugin plus an XPS calibration file - so you can apply a tailored flattening curve inside your DAW or export the profile to third-party EQs.

Build Quality & Protection

Construction is heavy-duty without being overbearing - the walnut cups look and feel premium and the stainless spring-steel yoke gives the whole headset a dependable, serviceable character. The earpads are a hybrid leather-and-velour design that balances seal and airflow, and mounting hardware is straightforward to disassemble with common tools if you want to swap pads or replace the cable. There is no hard travel case in the standard package I tested, so I treated these as studio-only gear rather than road companions.

Comfort & Portability

At roughly 420 g the S5X sits in the heavier end of over-ear studio cans, and you feel that mass after a few hours - but the headband suspension and deep pads mostly offset the weight and keep fatigue at bay during marathon mix passes. Clamping force is set intentionally to achieve accurate acoustic sealing, which means some users - myself included during the first day - may notice a firmer grip that relaxes after a short break-in period. Because they are open-back and not packaged with a hard case, I treated them as semi-portable studio monitors you bring between rooms rather than a travel headphone for commuting.

Real-World Experience

I used the S5X for mixing pop, acoustic, and short Atmos checks, and they consistently delivered a very usable, objective view of balance - mids felt particularly even and the stereo image was wide and stable, which helped place small spatial elements without resorting to exaggerated panning. Low end is present but leaner than consumer cans, which forced me to pay attention to sub and low-mid balance on my speaker checks - a productive constraint for translation. When I engaged the unit-specific calibration file the perceived balance tightened further; bass and treble nudges became more predictable across playback systems in my tests.

The Calibration Workflow

The USC approach is simple in concept - OLLO measures your serial-numbered unit and issues an XPS file plus a plugin (AU/VST/AAX) to apply the correction - and in practice it made a notch of difference to the things I care about most: stereo placement and low-mid balance. I ran the plugin in a DAW session and also exported the XPS data to a parametric EQ for system-wide use; both routes reduced small unit-to-unit variances and made reference listening feel more repeatable. The workflow is not instantaneous - you must import and activate the key - but it's a tangible benefit if you value consistent reference across units.

The Trade-Offs

The S5X is honest in its aims - a studio tool rather than a fun-sounding headphone - so listeners expecting warmth or low-end indulgence may find it lean and matter-of-fact until they intentionally EQ for excitement. The weight and firm clamp that help the cups sit properly for accurate response may be a negative for smaller heads or for listeners who prefer a very loose fit. Finally, because the design prioritises serviceability and a controlled open-back radiation pattern, there are some mechanical quirks in cup rotation and tilt that felt stiff to me at first and required a little adjustment to match my head shape.

Final Verdict

The OLLO Audio S5X 1.1 is a clear-minded studio headphone aimed at engineers and producers who want a flat, spatially faithful reference for stereo and immersive projects. I found them to be accurate, serviceable and refreshingly unglamorous - in a good way - with the USC calibration providing a useful final step toward repeatable listening. If you mix in untreated rooms or run lots of binaural/Atmos checks and value the idea of unit-specific correction, these are very strong contenders; if you want plush consumer bass or ultra-light comfort for all-day casual listening, you may prefer a different tool.