Bellos Audio X4 – Sound
Testing Equipment: FiiO K9 Pro ESS, Topping G5, Chord Mojo 2, System-wide Audioquest Cables, and several aftermarket tips & cables.
The Bellos Audio X4 is a delightfully tuned IEM. It features a neutral-warm signature with a smooth yet detailed sound. Its presentation is very fluid very coherent, and furthermore, it is a good all-rounder that can keep you excited no matter the genre. Bellos nailed the ‘easy-to-enjoy’ kind of signature with the X4, but most importantly, this presentation is backed up by a solid set of technical skills. The X4 feels spacious with a wide and deep stage, offers good PRaT, and, most importantly, excellent stereo imaging. Let’s look closely.
Bass
Starting with the lowest lows, the subs of the X4 are not elevated or aggressively tuned. The X4’s bass tuning contrasts industry trends, especially compared to Chi-Fi monitors, where we usually see an elevated sub-region to improve the perception of dynamics. On the contrary, the X4’s sub-bass follows the rest of the region from a step back. The X4’s overall bass tuning is smooth and natural. The bass has good weight and adequate extension. It is not the quickest bass I’ve heard, but it charms you with its smooth nature.
The mid-bass is ever so slightly elevated to give the finely balanced midrange instruments the necessary thickness. Bellos found a great balance here, but X4 left me wanting for slightly more sub-bass quantity. As for the texture, if you pair it up with a proper source such as Chord’s Mojo 2 or Topping’s G5, you get an adequately detailed yet smooth overall bass response that scales well with different genres. In my humble opinion, this region is the weakest link of the X4, and you’ll understand why in just a second.
Midrange
The midrange of the X4 is impressive. The female vocals are smooth, detailed, and articulate. The X4 reproduces female vocals with finesse; it reflects in a breathy and euphonic way without being too harsh or sibilant. The male vocals sound natural, and there is no over-pronounced thickness here. The body/weight of the midrange is well done, and the mid-based instruments have a nice, sweet tonality that takes the listener away.
The reproduction feels organic and natural, which I find very hard to achieve in IEMs because of their tricky nature and acoustic limitations. The upper midrange offers good extension, and X4 cuts the extension off just below the ‘hot’ area to provide an extended yet balanced upper midrange performance. The resolution and clarity of the entire midrange are pretty good, and combined with X4’s spacious and relaxed signature, the upper midrange has plenty of space to shine. The hi-hats and cymbals bounce around the spacious stage, creating an impressive sense of height. All in all, the midrange impressed me a lot, and it is safe to say that this region is one of the highlights of the X4.
Treble
I found the X4’s highs excellent. This region is hands down the most impressive side of the X4 for several reasons. Firstly, the treble feels very natural. It disperses naturally without any edge. The X4 reproduces one of the most extended and smoothly rendered treble I’ve ever heard. It does not stand out from the rest of the spectrum – it is neither recessed nor too prominent. Still, it just sounds very extended and detailed while maintaining a natural and musical tonality in a way that I don’t hear very often.
The texture feels natural, the resolution is utterly impressive, and, oh boy, it extends. The realism of the treble is the most important highlight of the X4, in my opinion. It is delicate, open, natural, and smooth at the same time. Well done.
Technical Capability
These are one of the best IEMs in terms of stereo imaging. The positioning of the instruments and the stage dimensions are really impressive, and I believe it has something to do with its tubeless design. The width, height, and depth of the soundstage are impressive, more so than any sub-thousand dollar IEM on the market, and the image it projects is so accurate and separated that I almost get a feeling I’m listening to my Focal Alpha 80 studio monitors instead of IEMs.
As for PRaT, due to the smooth and conservatively tuned bass range, the dynamism and PRaT feel like they need to catch up, especially compared to the amazing staging these offer.
Comparisons
vs. ThieAudio Monarch MKIII ($999 USD)
The Bellos Audio X4 and ThieAudio Monarch MKIII are both stellar IEMs, but they cater to different signature preferences.
The X4 is a masterclass in realism and naturality. It features a neutral-warm signature, ensuring a smooth yet detailed sound that remains engaging across various genres. The bass, while not the quickest, is charmingly smooth, contrasting with the industry’s inclination for elevated sub-bass tuning. The X4’s midrange and treble are its crown jewels, especially in its reproduction of female vocals, which are rendered with finesse, avoiding any harshness. The treble, while extended, remains natural, organic, and detailed, providing listeners with a delicate and open sound. On the technical front, the imaging and soundstage performance of the X4 is stellar.
In comparison, the Monarch MKIII is a dynamic powerhouse that is fun to listen to with less concentration on naturality and musicality. It’s engaging, with a pronounced bass that’s both deep and impactful, making it a better choice for bass enthusiasts. The MKIII’s midrange is clean, with a touch of warmth, and the upper mids give instruments and vocals an added edge, enhancing the overall resolution. The treble is where the MKIII truly shines, offering a vivid and energetic sound without veering into sibilance. However, it does not have the X4’s natural and organic treble tonality. The X4 offers a more natural and realistic reproduction both in the midrange and treble regions.
On the technical front, the MKIII showcases excellent agility and control and offers superior PRaT compared to the X4. While both IEMs have good imaging, the holographic soundstage and the positioning accuracy of the X4 are superior compared to the MKIII. The MKIII’s more dynamic and bass-forward presentation contrasts with the X4’s refined, more natural, and smooth signature, making the choice between them a matter of personal preference. Both IEMs, however, are easy to recommend in this price bracket.
vs. SWEEAR Audio Aurora ($2,499 USD)
While both lean towards a neutral-warm signature, they offer different listening experiences.
The X4 offers a musical yet detailed sound that is versatile across genres, making it a great all-rounder. This ‘easy-to-enjoy’ signature is backed by solid technical prowess. In contrast, the Aurora is smoother, providing a slightly warmer sound and a more recessed upper midrange and treble regions.
In the bass department, the X4 stands out with its smooth and natural presentation, avoiding the industry trend of an elevated sub-bass. While not the fastest, its bass charms with its smoothness. The Aurora, on the other hand, delivers an impactful, bold, and thick bass, with its power originating from the sub-region. It impresses with its controlled and impactful bass response. Resolution-wise, they are on par.
The X4’s midrange is a highlight, impressively rendering both female and male vocals with finesse and naturalness. Instruments in this range have a sweet tonality that captivates the listener. The Aurora’s midrange is warmer and tends to over-smoothen some tracks, especially those that thrive on upper-mid energy. The X4 feels superior here, especially in the upper midrange area, which is masterfully extended yet smooth.
Regarding treble, the X4 shines with its natural dispersion and impressive extension. The Aurora, while not the most extended, offers a treble that’s both clean and smooth. It is slightly more recessed in comparison and feels less spacious than X4.
On the technical front, the X4 features one of the best stereo imaging capabilities, with a soundstage that feels expansive in all dimensions. The Aurora, while less expansive, offers a soundstage that’s wide with good depth, ensuring instruments have good spacing. PRaT-wise, both monitors offer adequate performance. The X4’s positioning and accuracy feel slightly better, especially with congestion-prone genres.
Last Words
Bellos Audio X4 stands as solid proof of the Bellos brothers’ expertise in the audio field. With its neutral-warm signature, it offers a listening experience that’s musical, detailed, and smooth, suitable for a wide range of genres. Its expansive soundstage, precise stereo imaging, and exceptional treble set it apart in the crowded IEM market.
Combined with a design incorporating many industry-first technologies, personalized touches, and a range of quality accessories, the X4 is a great choice for audiophiles seeking a solid IEM with a realistic, easy-to-enjoy sound signature. I definitely recommend trying it, and if you’ve never ventured into CIEMs, the X4 is an excellent place to start.
Pros
– Great sound quality
– Excellent soundstage & imaging
– Natural and musical presentation
– Excellent comfort
Cons
– Limited customization options
Page 1: Bellos Audio, The X-Series, Bellos X4, Packaging & Accessories, Design & Comfort
Page 2: Sound, Low, Mid, High, Technical Capability, Comparisons, Last Words
