Ollo S4 and S4R Review

Ollo S4 out of the box, with a pouch, cables, and documentation.

Just before the COVID-19 outbreak took our lives for a journey into the unknown, I was getting ready to work on a few new projects that required some quality headphones for mixing and recording purposes.

My good old Sennheiser HD650 were temporarily out of order, and I thought it would have been the right time to try something new. I had heard about a new boutique company from Slovenia, Ollo, and I decided to check out their S4 and S4R models.

Ollo describes the S4 (open back) model as ideal for mixing and mastering, while the R in the (closed back) S4R model stands for recording. Both headphones are hand-made in Slovenia and share most of the features, except for the open vs close back deign.

Ollo S4

They’ve Got The Look

In terms of aesthetics, it was love at first sight. These headphones are a triumph of walnut wood and stainless steel, with the headband made of faux-leather. Solid stuff, no plastic. Impressive, to say the least, especially considering Ollo is a small new company.

Wood and steel also mean that these headphones are not as light as some of the other cans I’m used to (S4 and S4R both weigh 310 g each, 11 oz approx.).
That said, I find they strike a good balance between build quality and comfort. I think the size of the earpads works fine for most people, but if you have bigger than average ears (or a bit pointy) you might have to adjust them once in a while, so to get a more comfortable fit.

Ollo S4R

The only real weak spot is the steel arch/headband. It tends to resonate when touching the unit. Not a deal-breaker, but a bit annoying for a quality product like this.

Ok, But What About The Sound?

So, look-wise, these Ollo headphones are quite impressive, with just a few niggles. But how do they sound? Are they neutral as the company claims? On the web, you’ll find some detailed analysis of the frequency response so that I won’t go into that. As a musician/producer, I’m usually more interested in my subjective perception of the headphones I’m using, rather than the graphs.

I would describe the sound of these Ollo headphones as pleasant and effortless. I wouldn’t use the word neutral, also because I’m not a big fan of it when it comes to music and audio. If you, like me, come from a Sennheiser background, you’ll probably find the Ollo a bit darker. But don’t let these words mislead you. These are certainly not one of those ‘hyped-bass with fake-soundstage’ headphones that cater to the (young) hip-hop/EDM crowds.

Once I got used to them, I found the Ollo quite true to the source and versatile. Besides my projects (in this case, ranging from indie rock to electronica artists), I used the Ollo extensively with Tidal master quality albums (from classical and jazz to pop-rock classics and techno).

Playing with Arp Odyssey and Ollo S4R while everybody’s sleeping

Would I mix on the S4? I did and with excellent results. My mixing environment, while working on these projects, was less than ideal. Using quality headphones such as the Ollo S4 made the work more natural and enjoyable. The Ollo S4 offers an honest representation of the audio program, no resonance, a solid stereo image, and no listening fatigue.

As for the S4R, I was particularly impressed with the isolation/noise cancellation Ollo has been able to achieve. The singer and the musicians I was working with found that very helpful. I’ve also been using the S4R in my home studio lately while recording some vocoder and other electronic instrument tracks. Being at home often means having to deal with the piercing sounds of a loud 1-year-old baby. Well, the S4R proved to be a lifesaver!

You can even ask Ollo to print your custom logo on the S4R!

Next Level

Despite the fact Ollo claims their S4 and S4R are neutral and don’t need any extra EQ treatment, I decided to take them for a spin using Sonarworks Reference 4. At ANR, we’re big fans of this brilliant audio calibration software – see our Sonarworks Reference 4 review. Reference 4 includes presets for both S4 and S4R, so I thought, why not give it a try?

The results were very interesting and brought the S4 close to what I used to get from my HD650. The bass is less dominant yet more focused (also some sub-bass frequencies seem clearer) and the mid-high frequencies appeared more ‘natural,’ for the lack of a better word.

Sonarworks Reference 4 interface

This doesn’t mean I wouldn’t use the S4 on its own, quite the contrary. I think it’s fantastic to have options, but you don’t necessarily need to use them ALL the time. So, if you happen to be a Reference 4 user, I would recommend trying the Ollo presets – they will add even more value to your headphones.

If you are not, and you would like to buy Sonarworks Reference 4 to calibrate the sound of your speakers, think of the headphones presets as a welcome bonus. Oh, before I forget: Sonarworks also offers the Sonarworks Reference 4 Headphones edition, a cheaper version (only $99) of their software that you can only use to calibrate your headphones, not the speakers.


Ollo might be the new kid on the block, but the S4 and S4R (both 289 €) are far beyond what you would expect from a newcomer. They look fantastic, and they strike a great balance between design, comfort, and tone. Despite some niggles, if you’re looking for quality yet affordable headphones for your mixing and recording sessions, you should check these out. After all, you have nothing to lose. Ollo offers a ‘try before you buy’ option, which allows you to receive the headphones paying only 99 € + shipping.

After 30 days, you’ll pay 15,90 € each month, for 12 instalments if you do decide to keep them. If you don’t, you’ll send them back and get the 99 € back. I wish more companies would offer such a customer-friendly option! Oh, one more thing: if you’re ordering the S4R, you can get your custom logo printed on them. How cool is that?

To learn more and order the Ollo S4 or S4R, please visit the official website.

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