Sound –
Tonality –
The IO is one of the more controversial IEMs released recently, and in listening, it is surely both unique and inviting, however, not without its quirks. At a glance, the IO is a W-shaped earphone valuing cleanliness and clarity, with fair brightness through its top end. This is counterbalanced by a lightly warm mid-bass that keeps the sound fairly natural and contributes to ample vocal body. The earphone is particularly forward through the midrange on behalf of 1 and 4KHz peaks, delivering clear, prominent vocals. A smoother lower-treble prevent excessive midrange thinness and fatigue, especially with the aforementioned 4K peak, while a moderate bump to the middle-treble generates heaps of air and headroom alongside TAEC. As this continues into the upper registers, the earphones have a delightfully sparkly presentation that high-end Campfire earphones are renowned for.
Bass –
The IO offers adequate sub-bass extension combined with slightly elevated quantity that offers a bit more weight than neutral but not a huge amount of slam or rumble. As such, the majority of the IO’s low-end body is derived from its mid-bass that is pleasantly full and a touch warm, so the earphone never sounds anaemic or thin through the lows. Meanwhile, the upper-bass sits at a neutral level to maintain a clean tone and adequate bass/midrange separation. The result is a slightly warm low-end with neutral note size that doesn’t come across as especially emphasized but well balanced with its forward midrange. The added warmth also helps to imbue body into the IO’s sound, maintaining a natural-sounding presentation.
As the IO has excellent control and lightning-fast decay, it rewards listeners with excellent definition and detail retrieval. Due to its natural mid-bass tuning, the IO doesn’t wear on the ear, delivering a slightly smoother-texture. This grants it great genre versatility, suiting both fast, complex rock and electronic and slower jazz and blues. Those wanting visceral rumble and impact will want to look towards a hybrid or dynamic earphone. However, the IO is a very well executed neutral-orientated tuning that is clean and well-detailed while upholding natural tone and body.
Mids –
Vocals stand out to the listener first on behalf of their excellent clarity and somewhat forward positioning. This is derived from a slightly recessed lower-midrange that builds to large twin peaks through the centre and upper-midrange. As it isn’t linear or gradual in its emphasis, the IO doesn’t possess an accurate midrange timbre nor does it sound especially natural. Rather, it generally sounds slightly thin and cool which yields extreme cleanliness without an ounce of muffle or veil to contaminate its image. A smooth lower treble prevents rasp and hollowness. Furthermore, upper-midrange extension is terrific and, though vocals are prone to sounding a touch diffuse due to lack of density or warmth, they are delicate, transparent and pure.
In direct comparison to more linear earphones, the IO is prone to sounding a touch honky and even metallic on poorly mastered tracks. However, once adjusted, the benefits of its tuning are easy to appreciate. Male vocals are also less affected by this as they are a touch warmer on behalf of the IO’s mid-bass tuning imbuing additional body. The IO’s midrange may polarise as its sculpted tuning is inevitably a double-edged sword. Still, there are plenty of earphones delivering flavours of balance and linearity but few I’ve heard that deliver vocals with such glossy sheen. The IO is a unique experience.
Highs –
The IO is a brighter earphone with a rather sculpted treble. It implements a sharp dip between the upper-midrange and lower-treble preceding a small rise at 5KHz before a less emphasized 6KHz. This is a wise tuning decision that prevents vocals from sounding overtly sibilant or over-articulated. Meanwhile, clarity is retained and treble body isn’t overly thinned out as the 6KHz region is well-controlled. The same can be said for the middle-treble that sees moderate uniform emphasis. As there are no ugly peaks, the IO’s brightness is fairly innocuous, especially when contextualised by its warmer bass. The result is a high-end that is clear, crisp and completely lacking of warmth, however, with a distinct lack of lower-treble aggression or middle-treble glare. Accordingly, it never becomes sharp, splashy or brittle, all the while providing ample bite and attack, with a concise presentation of strings and percussion and adequate treble note body.
Understandably, the IO doesn’t have the cleanest background or the most delineated layers. Rather, its sustained middle-treble emphasis permits great headroom and air that operates in tandem with strong extension into the highest registers. Upper-treble emphasis isn’t immediately apparent, however, characteristic to Campfire earphones, there is no shortage of sparkle or energy due to its extension. The IO’s abundance of air and linear extension into the upper-treble combined with ample resolving power redeems micro-details in the background that contributes to a large sense of space. This tuning also maximises detail presentation even if actual detail retrieval is about what I would expect from a well-performing earphone in this price tier.
Soundstage –
Certainly a strength of the IO, the soundstage is spacious, a quality enhanced by excellent separation. Width extends a fair margin beyond the head and depth, though prone to bringing vocals to the fore, is similar, providing a well-rounded and immersive stage. Imaging is sharp if not entirely accurate due to the earphone’s forward vocals and inter-dispersed layers that tend to work more as a cohesive whole than a real separated band. Nonetheless, the IO’s presentation never devolves into a wall of sound, rather, it is hyper-separated as a result of its cleanliness, mostly neutral note size and large space within which to place elements. Centre image is strong and directional cues are very sharp. The IO risks sounding even a touch diffuse and, at times, disorganised due to its thinner and more forward nature, though its resolving power ensures details aren’t lost in the mix.
Driveability –
The IO sports a 26ohm impedance and 109dB sensitivity. Similar to most BA Campfire earphones, it is easy to drive and sounds just fine out of a portable source. The IO also wasn’t overly affected by output impedance in my testing, sounding almost identical from the 10-ohm Hiby R6 as the sub-1-ohm Fiio X7 Mk2, losing just a touch of sub-bass and creating a slightly smoother treble. Nonetheless, the IO benefits from a resolving source in terms of treble extension and soundstage. The IO is one of the less source discriminating earphones I’ve tested and users shouldn’t feel that an amplifier is necessary to extract a faithful signature. Still, it remains quite a resolving earphone that scales well with higher-end sources.
Comparisons –
Campfire Orion ($349): The original entry-level CA earphone, the Orion only sports a single BA driver and none of the snazzy tech brought by campfire’s latest. It pursues a more reference sound and is more linear by a large margin. The Orion pursues a vocal-forward sound where the IO comes across as more W-shaped with simply a focus on vocals; it is more sculpted and engaging which emphasizes its wider bandwidth. It has a large advantage in bass extension though both have punchy mid-bass of similar quantity. The Orion has less upper-bass so its tone is more neutral. The IO is more detailed, digging deeper and redeeming more note texture while the Orion is cleaner with slightly harder hitting mid-bass. The Orion has a more linear midrange with just a small centre midrange push that makes it slightly vocal-forward. The IO, on behalf of its more present bass and treble, comes across as a touch more balanced.
However, as the Orion has fewer peaks and valleys, it has the more accurate timbre. Meanwhile, the IO has more clarity and also a warmer tone, sounding slightly fuller and smoother where the Orion is cleaner and denser yet also raspier as its lower-treble is more forward. This grants it greater attack to treble instrumentation. Its treble is also cleaner with a darker background, however, it has substantially less extension than the IO, rolling off through the middle treble and lacking the headroom and air of the IO entirely. The IO is more resolving, but also clearly brighter and thinner. Still, it has more energy, sparkle and detail retrieval by a wide margin. The IO has a much larger soundstage than the Orion due to its added extension and though its imaging is less organised, it is more separated and resolving throughout.
Shozy BG ($280): The BG has a similar presentation but is more balanced and linear than the IO. The BG offers a touch more depth in the sub-bass but also slower decay so it sounds more dynamic but also slightly warmer and with a smoother texture. Though tuning is almost identical in terms of quantity from sub to upper-bass, the IO offers faster decay and, by correlation, delivers higher definition notes and a touch more low-end detail, though sacrificing dynamics to achieve this. Through the midrange, the BG is denser and smoother, it isn’t as honky but also isn’t as vibrant. The IO sounds clearer but also less consistent in terms of body, either coming across as a touch warm and full bass permitting or cooler and thinner on older tracks.
The BG is flatter for better or worse, but sounds a touch more refined overall if less extended and revealing at a glance. Up top, the BG implements twin peaks with an emphasis on the lower-treble, granting it more attack and crispness. Meanwhile, the IO is a bit thinner but also has more treble clarity as its emphasis resides mostly in the middle-treble. The BG has a darker background and similarly excellent extension just without the air and sparkle that makes it so apparent on the IO. The result is a more separated treble on the BG but also a slightly sharper foreground that can grate on certain tracks. The IO has a slightly larger soundstage and superior separation while the BG has more accurate imaging with more defined layers and sharper directional cues.
Oriveti OH300 ($300): The OH300 offers a more balanced sound with a heftier low-end on behalf of its hybrid driver setup. It has more sub-bass extension and considerably more quantity granting it greater slam and rumble. The Oriveti also has a touch more mid-bas though it also has less upper-bass so, although it is fuller, its tone is actually more neutral than the IO’s. The IO, on the other hand, has faster decay and a touch more control, trading dynamics and depth for greater definition and detail. The OH300 also has a centre-midrange boost, however, its emphasis are more progressive, and it has more accurate body and a somewhat more natural presentation as a result. Both earphones are very clear and clean, the IO is noticeably thinner, however, it is also a touch more transparent. Neither have huge rasp or hollowness as they both feature smoother lower-treble, though the OH300 is the smoother earphone by a fair margin.
Contrarily, it does sacrifice some clarity and crispness to achieve this. The IO has more aggressive lower-treble, it is crisper but also thinner. Despite having a lower driver count, it is also a touch more detailed. The middle-treble is where the earphones differ substantially, the OH300 sounding very dark, clean and delivering very defined layers. The IO rather offers a lot more headroom and air but sacrifices some separation in so doing. The IO has a touch more extension and is more resolving of fine details, but again, sounds less organised. This grants the IO a wider stage though the OH300 has slightly more coherent imaging and both feature excellent separation.
Early Verdict –
Audio rewards the passionate enthusiast with the same beauty as any other hobby, variety and choice. Due to its technical undertones, however, we often lose sight that there is allure in what is different, not always what is best at a technical level. It’s also important to consider different tastes in music and the way it is represented. As such, I am not one to reprimand Campfire Audio’s intention to spice up the audio world, not only with colourful designs but also sounds. The IO exemplifies this as their bombastic dynamic driver and hybrid designs have before. On a technical level, it also represents a huge step up from the similarly positioned Orion, offering very competitive treble extension and detail retrieval. Its tuning is completely unorthodox, yet completely unique. Its eclectic emphasis’ and troughs surmount to a sound that simply works. Midrange timbre is off though its forwardness is counteracted by bass warmth and treble smoothness. The background is bright, however, its extension ensures that no cheating is involved to achieve a wide-open soundscape and abundant sparkle. The IO is not for those seeking absolute linearity, balance or realism, but rather an exciting listening experience charged with quirk and character.
The IO can be purchased from Campfire Audio for $299 USD. I am not affiliated with Campfire Audio and receive no earnings from purchases through this link.
