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Ollo Audio S4X review : As good as it gets

Ollo Audio, Not many are aware of this brand, they are not a huge brand with a lot of wave behind them but they are something. Originating from the beautiful country of Slovenia, surrounded by the Alps, Ollo Audio is the home to one of the best headphones for under $500. Ollo have been in the market for a few years but have not caught a lot of attention, they do not ride the hype waves. Their headphones are not aimed towards the mass market with a thumpy or fun oriented sound. All of the Ollo audio headphones are aimed at studio use and critical listening. Ollo as a brand do not make a lot of models in a variety of price ranges, they only have had 3 models and they pay a lot of attention to quality control and details. Their headphones look aesthetically classy with a retro kind of Vibe. Interestingly one can buy whatever spare parts they desire from their website and.. The headphones themselves have 5 years of limited warranty!! 5, that is one year, five times (This does not cover the pads and cables though).

Ollo has only two Headphone on sale now, one is the S4R and their flagship the S4X reference headphone, which I am reviewing here. It does not have any options for the wood but hey, the stock wood looks classy too. Priced at 399 Euros these headphones face some competition from another growing brand, Austrian Audio HI-X55 and other headphones in its price range like Hifiman Sundara, HD600 and a few more.

Get one for yourself from here:


P.S. I reached out to OLLO Audio for the S4X review and they responded kindly.


There isn’t a lot of stuff inside the box, a cable, a 3.5mm to 6.5mm adapter, a carry pouch and a few documents rounds up the list of accessories.


The Ollo audio ships with a 200cm/78inch long basic looking cable, with 3.5mm TRS and dual 2.5mm TRS terminations, nothing fancy here. It has external braiding from the 3.5mm jack till the Y splitter, it protects the wire from accidental damage and wear too. But due to this braiding the cable ends up being slightly on the stiffer side.  The splitter is small and barely has any weight to it. The cable above the splitter is kind of flashy with red rubbery coating over the wire which gives it a bouncy feel but doesn’t result into any microphonics thankfully.

Even when the cable has L/R markings, the ear cups don’t have anything like that. Thanks to frequency matched drivers plug any on any side and it is good to go.


I already have a very similar looking headphone in my inventory with a slightly different type of wood. Aesthetically the S4X looks more premium with a slightly darker but natural and sober looking wood. The drivers are held in place with two screws on both sides of the cups. The open style back plates give S4X a retro classic vibe. The stainless steel head bend feels a lot sturdier and stable. The spring loaded leather headband does not have any cushioning but due to the wider design feels very comfortable. The headband is held in place with simple screw which can be changed without any problem.

Ear pads have a hybrid design with velour on the face and artificial leather on the sides. With an outer diameter of 90mm and inner diameter of 55mm the Level of comfort is fairly good for a few hours but have to be adjusted after that. I would have liked a slightly bigger pad. The size is somewhere in between on and over ear sizes.

In their words:


“Timelessness of stainless steel coupled with luxury nautical leather and velour for maximum comfort. Paired with a smell of a fresh sustainably sourced wood.”


“Custom designed velour earpads fit around your head snuggly while the self-adjusting strap provides for a perfect fit. Combined with a balanced sound, it will enable you to work on headphones for hours.”

Ollo S4X’s refreshingly simple yet intriguing deign has been awarded with German Design council recently.


Since i have bought a few LG devices with dedicated DACs they have become my first source of music. The S4X sounds kind of edgy with mobile phones, be it the Vivo V19 or LG G7. The S4X demands a bit of power, even when the rated impedance is at just 32ohm it is not the easiest headphone in the market and doesn’t comply excellently with weaker sources. Not that the S4X doesn’t get loud, it gets fairly loud with the mobile devices but the sound is not at its prime, it kind of feels being dragged, notes are not full enough and doesn’t have the best tonality either.

Driving it out of a dedicated DAC/Amps delivers a much more desirable output. It is an open back headphone after all and is not meant for outdoor use. Driving out of the Burson Audio Playmate is a pleasant affair. It starts to behave well with excellent details and control over notes. It does not feel like being forcefully pushed any more.

Driving the S4X out of a dedicated dap like Shanling M6 yields excellent resolution and details. It starts sounding a bit more mature and perfectly reflects the true characters of the DAP without breaking a sweat.



Suman Sourav Meher

Suman Sourav Meher

My humble audiophile journey started in 2010, when I was in college, where I fell in love with the elements, nuances, and variations of this mesmerizing world. The ability of tiny earphones to recreate amazing sounds made my bad days tolerable and good days better! Now I am a full-time audiophile with a preference for musical tracks, especially vocals and engaging ones. I must admit I am addicted, but not to drugs or alcohol, but to earphones. Come join me as I share my experiences, bad or good, and let’s have some fun!


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