Ollo S4X Studio Headphones Review: Precision Sound for Mixing and Mastering

Explore the detailed sound and build quality of Ollo S4X headphones designed for mixing and mastering music with precision.

Introduction to Ollo S4X Headphones

Who doesn't love headphones? Whether you're a casual listener or someone who crafts music, the right headphones make all the difference. Today, we dive into the Ollo S4X from Ollo Audio—a model tailored for music creators who demand clarity and accuracy. Priced around $400, these headphones are compared to competitors like the HIFIMAN Deva ($350), Sivga P-II ($400), iBasso SR-2 ($500), and Adam Audio SP-5 ($500). Testing gear includes Singxer SDA-2, FiiO M11 PRO, and iBasso DX220 MAX.

What stands out about Ollo Audio is their commitment to reliability and customer support. They focus on musicians, mixers, and mastering engineers rather than just audiophiles. Their modular headphone design makes repairs easy—you can swap out the headband, driver, or any faulty part in under a minute. If issues arise, Ollo Audio is ready to assist without hassle.

A quick note: This review reflects my honest opinion. I have no affiliation with Ollo Audio beyond receiving a sample for testing. The goal here is to help you find your next go-to headphones for music production.

Packaging: Simple Yet Sustainable

Let's talk packaging first.

The Ollo S4X comes in one of the simplest packages I've ever seen in this price range—plain cardboard that's a bit tricky to reassemble. But here's the silver lining: the company prioritizes eco-friendliness by using recycled materials. A small sacrifice for a greener planet!

In terms of accessories, it’s pretty barebones—just the headphones and a cable. Many headphones in the $400 ballpark include spare ear pads, additional cables, or carrying cases. However, the included cable is of high quality and easily replaceable, especially if you're into aftermarket cables.

Technical Specifications and Care Instructions

• Do not press on the ear cups to avoid creating air pressure that can damage the driver membrane.
• Avoid pressing the headphones tightly against your ears.
• Never lay the headphones flat on a table.
• Use care when connecting or disconnecting cables to prevent stress on the components.
• When transporting, ensure the ear pads aren't compressed against hard surfaces—ideally wear them around your neck.
• Since these headphones are made of wood, keep them away from direct sunlight and rain.
• If water spots appear, you can gently treat the wood with tung oil to restore its finish.
• Replace ear pads after about 1000-1500 hours, as worn pads affect bass response. Replacement parts are available on Ollo’s website.

Build Quality, Aesthetics, Fit, and Comfort

Since reviewing the Dan Clark Aeon Flow, I’ve been cautious about proprietary cables, but Ollo designed the S4X to have easily replaceable cables. Plus, the included cable and ear pads are impressive quality.

The S4X features an open-back design that actually leaks less sound and isolates better than most open-back headphones. Comfort is generally good; however, those with larger ears might find the fit a touch snug. The fit generally embraces the ear for most users.

Their power demands are moderate—these headphones aren’t the easiest to drive but perform steadily across various sources. A minimum recommendation would be the FiiO K5PRO or Lotoo Paw S1 for amplification, while higher-end sources unlock better dynamics and punch. The detail level and sound signature remain consistent regardless of the source, which is a huge plus for mixing and mastering.

Crafted from wood and metal with dynamic drivers, these headphones have a solid, weighty feel that speaks to durability and high build quality—some of the best I’ve tested.

Sound Quality: Detailed and Neutral

The Ollo S4X sound signature is forward, ultra-detailed, clear, and dynamic with a slight texture. Its tonal balance is neutral, with a level of detail that punches well above its price tag. The sound leans closer to planar magnetic headphones than typical dynamic drivers, reminiscent of the Audeze LCD-MX4.

Bass is tight, fast, linear, and not overly warm. The mids have good substance but aren’t emphasized. Bass presence is faithful to the original mix—if the bass isn’t there, the headphones won’t add any. This makes the S4X excellent for mixing and mastering, although casual listeners may find it a bit dry. Metal tracks sound precise and energetic, pop is accurate, but hip-hop may feel somewhat bass-light.

Midrange frequencies stand out as the most prominent part of the sound signature, which is unusual. They are clean and detailed without harshness—similar to the smooth presentation of a Chord Mojo DAC. The dynamics are good, typical of dynamic drivers, though mids can feel a tad grainy at times. The S4X excels at revealing mixing and mastering flaws, making it a valuable tool for professionals.

The treble is the least exciting aspect—smooth and low-energy, great for long listening sessions but could feel dull if you like a bit of sparkle. Personally, I prefer listening to the S4X at night when I want to relax—their jazz and classical reproduction are stunning. However, metal, rock, and punk may miss that sharp upper-edge, while pop can overly highlight vocals.

Comparison with Other Headphones

The Ollo S4X competes in a crowded field. Here's how it stacks up against some key rivals:

• Ollo S4X vs iBasso SR-2 ($400 vs $500): SR-2 offers better comfort and more accessories. It has a more laid-back, natural sound with brighter highs. While SR-2’s soundstage is larger, the S4X boasts superior detail and texture resolution. Choose SR-2 for comfort and musicality; S4X for accuracy.
• Ollo S4X vs Sivga P-II ($400 vs $400): Sivga P-II is more comfortable, better built, and includes a superior stock cable. Sivga sounds more spacious and musical with stronger bass and treble extension, resembling live performances. S4X offers a tighter, more precise studio listening experience with excellent instrument placement.
• Ollo S4X vs HIFIMAN Deva ($400 vs $350): Deva features larger ear cups, less isolation, and Bluetooth. Its soundstage is impressive, with more air and space. The S4X has a denser, more detailed low-mid range and excels at exposing mix flaws. Deva sounds more musical and open; S4X sounds clinical and precise.
• Ollo S4X vs Adam Audio SP-5 ($400 vs $500): Both are designed for studio use. The Ollo S4X wins for comfort and build quality with softer pads and better cables, though SP-5's packaging is more premium. Adam SP-5 is brighter with less bass and can sound fragile in mids. S4X offers better detail, natural sound, and longer listening comfort. SP-5 is great for spotting excessive treble; S4X is better overall for mixers and masterers.

Recommended Pairings for Optimal Sound

Pairing the S4X with the right source amplifies its strengths. Recommended combos include:

• Ollo S4X + iBasso DX220 MAX ($400 + $1880): This pairing delivers maximum dynamics, impact, and detail from a portable device. Though less bright, EQ adjustments can add top-end sparkle. DX220 MAX also doubles as a USB DAC for desktop use—ideal for a versatile setup.
• Ollo S4X + FiiO M11 PRO ($400 + $650): The M11 PRO offers a brighter, more open sound complementing the S4X’s warm, smooth signature. It’s a great balance for both critical listening and mastering.
• Ollo S4X + Singxer SDA-2 ($400 + $700): A balanced DAC/amp that provides a natural sound with a warm midrange emphasis. This combo delivers clean, dynamic, and controlled sound—perfect for studio work without breaking the bank.

The S4X remains stable and consistent across different sources, ensuring reliable sound for any setup.

Value and Final Thoughts

The Ollo S4X offers outstanding value, packing many virtues into a modest package.

Yes, the lack of spare ear pads or cables is a downside, but the headphones' sound, performance, and build quality more than compensate. Honestly, I’m impressed enough to place the S4X in my audiophile hall of fame.

They are slightly snug, not fully open-backed, and provide some isolation with minimal sound leakage. The premium ear pads add to the comfort for long sessions.

Their sound is balanced, focused on mids, making them excellent for mastering and extended listening—just don’t expect a lot of treble sparkle.

If you're starting out in mixing or mastering or need a budget-friendly, high-quality headphone that performs close to much pricier models, the Ollo S4X deserves a serious look.

“The sound signature is forward and ultra-detailed, revealing mixing flaws with impressive clarity.” — Anonymous Reviewer

Conclusion

Are you a budding music producer or mastering engineer looking for headphones that blend accuracy with great build quality? Ollo S4X offers a compelling mix of detail, comfort, and value that can elevate your studio experience without breaking the bank. Ready to take your music craft to the next level?

FAQs

• What makes Ollo S4X suitable for mixing and mastering?
  The S4X offers a neutral, detailed sound with strong midrange focus, making it easier to spot mix flaws and subtle details.
• Are these headphones comfortable for long sessions?
  Yes, though slightly snug for larger ears, the high-quality ear pads and secure fit support extended wear.
• Can I use Ollo S4X with portable devices?
  They can be driven by portable players like iBasso DX220 MAX and FiiO M11 PRO, but smartphones may lack sufficient power.
• How durable are the Ollo S4X headphones?
  Made from wood and metal with modular parts, they’re robust and easily repairable if needed.
• Does Ollo S4X come with extra accessories?
  Unfortunately, no—only the headphones and a quality cable are included, with spare pads sold separately.

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