Product Strengths

• Versatile sound signature, going from bassy to neutral with the use of included tuning modules
• Excellent bass response with a dynamic driver, providing strong texture, deep extension, and impact
• Very good treble extension, air, and sparkle for detail retrieval without harshness
• Expertly captures the 64 Audio character of balancing pro audio sensibilities and a more audiophile-friendly sound
• Comfortable and durable design, with a lightweight anodized aluminum shell and well-thought-out accessories

Product Considerations

• Imaging and instrument separation are decent, but not standout for the price range
• Mid-range may sound a bit thin to some, with a more relaxed upper mid-range that results in vocals being a little bit on the husky side
• The nozzle doesn’t have lip holder and is a bit problematic
• Isolation isn't exceptional due to the apex module

Comparisons (according to reviewers)

• Vs 64 Audio Neo: U4S is preferred due to the U4S being the cheaper IEM
• Vs Thieaudio Monarch MkII: The Monarch is comparatively lean sounding
• Vs 64 Audio U6T: U6T is a little more neutral overall with a stronger technicality, but the U4S injects a little more fun into the sound
• Vs Campfire Audio Andromeda Emerald Sea: The U4S offers a more natural mid-range presentation
• Vs 64 Audio Nio: The U4s effectively undercuts the Nio by a third of the price with comparable sound quality
• Vs Custom Art Fibae 5: If you want technicalities and details, Fibae 5 is superior, if you want a very capable yet slightly musical and mainstream IEM, opt for the U4s

Takeaway:

The 64 Audio U4s is a well-rounded IEM that offers a fun and engaging sound signature with the ability to customize the bass response. With its comfortable fit and excellent build quality, it's a great option for those looking for a versatile and enjoyable listening experience.

Product Strengths

• Delivers a bass-intense sound with strong rumble and thunder, while remaining fast, impactful, and dynamic
• Offers a wide and airy soundstage with a holographic sense of separation, and precise imaging
• Provides a smooth and open midrange with a natural character, and excellent resolution and layering of instruments and vocals
• Includes Apex modules for altering the tonality of the sound
• Features a durable and attractive design with aluminum shells, and a unique abalone faceplate

Product Considerations

• May have a large upper treble peak that can cause a shimmery sibilant sheen to vocals, or make some instruments sound clicky or tizzy
• The bass response could be too impactful for analytical listeners
• The quality of the stock cable might not be worthy of the IEM's higher-end status

Comparisons (according to reviewers)

• Vs 64 Audio U12t: Volür offers something very similar, but with notable upgrades, especially in bass texture and tactile presentation
• Vs 64 Audio U4s/Nio: While Volür improves upon the U4s and Nio's bass, the difference isn't dramatic, and the U4s/Nio are arguably better tuned due to the absence of a big upper treble peak
• Vs FiR Audio Neon 4: The Ne4 has a stronger bass emphasis and warm color, while Volür has more natural timbre, and stronger vocal performance
• Vs Sennheiser IE900: Volür has a better-tuned upper midrange and more comfortable ergonomics, but the IE900 has more textured bass, and a controlled mid-treble energy

Takeaway: The Volür is a well-built IEM that delivers a bass-forward sound with a wide soundstage and excellent imaging, making music sound exciting and immersive. With the ability to change the sound with different modules, it is a flexible option for listeners who want to tailor their listening experience.

Product Strengths

• Beautiful aesthetic design, featuring a copper faceplate with the 64 Audio logo and a metal shell
• Comfortable and secure fit, similar to other 64 Audio universal IEMs, suitable for extended listening
• Bass is fast, clean, textured, and well-separated, without bleeding into the midrange
• Midrange is a highlight, with natural, textured, and realistic vocals for both male and female
• Treble is detailed, transparent, and sparkly without being overly aggressive, maintaining a crisp and rounded sound

Product Considerations

• The Solo sounds like many other existing 14.2 mm planar IEMs
• Soundstage width is average
• Eartip rolling may be required to find the best fit
• Slight metallic timbre to the sound
• The nozzle length and angle, as well as the connector housing on the shells, may cause the cable to hit the ear on the top

Comparisons (according to reviewers)

• The Solo has better resolution and accuracy, especially with complex tracks, while the 64 Audio U4s is more customizable and isolating with a more dynamic bass
• The Solo has a more tamed treble response than the 7Hz Timeless

Takeaway: The 64 Audio Solo is a finely tuned planar magnetic IEM that is both beautiful and comfortable. It offers a rich, detailed sound, especially in the midrange, making it a great choice for those who enjoy immersive and high-quality audio.

Product Strengths

• Improved cable with a more premium look and feel compared to previous 64 Audio cables
• Balanced sound with a blend of neutrality and musicality, revealing depth and complexity of music
• Slightly more bass presence and punchier bass than the U12T
• Non-fatiguing treble presentation that balances definition and accuracy without harshness or brightness
• The U6T offers a distinct blend of reference-level detail and emotional musicality

Product Considerations

• Soundstage and imaging are not as accurate or massive as the U12T
• The NEO has more bass emphasis than the U6T
• The mids are somewhat subdued, and this may not be to everyone's preference

Comparisons (according to reviewers)

• The U6T draws the majority of its inspiration from the U12T with a similar balance of neutrality and musicality, though the U12T has a more massive soundstage and accurate holographic imaging
• The U6T has fuller mids and a better-balanced treble with the bass compared to the NEO, which has stronger bass emphasis
• Both the Campfire Audio Andromeda and the U6T have strong imaging and soundstage, but the U6T has an advantage in resolution
• The U6T lands in the goldilocks zone between the Symphonium Helios and the Sony IER-M9

Takeaway: The U6T is a great IEM that provides a distinct blend of reference-level detail and emotional musicality. It is a great option to get into 64 Audio's IEMs, providing an immersive sound experience.

Product Strengths

• Fantastic bass response, especially the sub-bass, with great extension
• Well-tuned midrange, with a flatter lower-midrange and a gentle rise from 1-2kHz
• Comfortable due to the custom in-ear monitor (CIEM) fit and the Apex technology, which alleviates pressure buildup
• Top-notch build quality

Product Considerations

• Treble response may lack energy in the lower and mid-treble regions
• Timbre might sound somewhat plasticky
• Might require frequent cleaning, because earwax tends to build up easier on CIEMs

Comparisons (according to reviewers)

• Has a little bit more 100-200Hz than the Audio Monarch, which lends to a slightly warmer bass response

Takeaway: The A4s is a solid choice if a custom in-ear monitor with very good bass and a comfortable fit is desired. It's great for people who value strong sub-bass and a relaxed listening experience.