Campfire Audio IO - Reviews
Pros: Great detail retrieval. Wide soundstage. Beautiful color and accent choice. Fantastic packaging and great unboxing experience.
Cons: Sub bass is lean. Mids can be wonky at times. Requires tip rolling and cable rolling to make mids mostly normal.

I first saw the IO and instantly fell in love with the color scheme. After reading many reviews it seemed people were fairly conflicted on whether or not the mids were broken or just tuned strangely. After some time I decided to give them and the Polaris II a shot. I’ll say right off the bat the mids aren’t nearly as bad as some make it out to be. I made sure to listen to my UE TF10 which was know for being recessed in the mids but people didn’t make a big deal out of it back when they launched or became popular. The Campfire Audio IO is the current entry level iem CA offers. It runs a two BA setup for lows and highs. It comes in a beautiful red-maroon color with gold screw accents.

Comfort and fit- The new design has a slightly longer nozzle than the older CA iems and I have no comfort issues like I do with the Andros or nova of old. The IO is also a light iem so it can stay in the ear longer.

Onto the review of the sound! My personal preference are a dynamic hybrid iem where I get good hitting bass and have a brighter treble with decent mids. I listen to a lot of genres but I hover in the classic rock, blues and edm music with some rap here and there.

Gear used
iPhone X with headphone adapter, FiiO m11, smsl sh8/su8 combo.

Lows- The sub bass is really light but it’s there. The mid bass has a decent impact which feels more like a tease when you listen to music that you know has some sub bass and mid bass hits. You get the mid bass hit but no sub bass hit which is a bummer. EQ helps a little but I try not to eq if I can avoid it.

Mids- Mids are a hit or miss. With stock tips and the stock cable, I had male vocals that sounded fine but female vocals sounding slightly recessed. A switch from the stock tips to some out of my collection helped keeping thing in line with instruments. Using a null audio lune cable which has always emphasized the mids in other iems helped keep the female vocals in check.

Highs- Really clean highs and I didn’t feel any sibilance while listening to these. Detail retrieval was also fantastic! You can tell a bad recording with the IO which I find to be rare in the $300 and under range.

Imaging- Nothing out of the ordinary and all was well for the IO

Soundstage- Nice and wide. Not crazy wide but wide for the price range.

Cable rolling- The stock cable is perfectly fine and the mmcx connectors stay snug in the iems sockets. Cable rolling did help the mids and low end a little but I don’t think the IO requires it. Would be more of a want vs need.

Tip rolling- If you want more bass the final e tips they include work fairly well but I ended up swapping between the Dekoni bulletz in the 4.9 bore diameter or the spinfit cp145 which is a 4.5 diameter. Both had a better sense of space being wider bore size but didn’t do anything for the bass department.

Amping- Off the stock 3.5 cable the sensitivity wasn’t noticeable. Once I went balanced you got a very noticeable hiss but it disappeared with music playing. I felt more power did give better detail retrieval but that’s about it. The connectors are so tight that a/b testing took a little too long to really test for more differences.

Overall thoughts
I can appreciate the tuning of the IO. Minus a slight recessed mids and lean bass I can see someone looking for a neutral to bright sound really liking these. The packaging and unboxing experience was neat and I enjoy the thought that went into that. CA also includes a nice selection of tips, a storage bag(looks like a coin purse) I would never use and a cool little CA logo pin as well. Unfortunately the sound signature isn’t for me but with the looks of the IO and the fact it’s a US made product I think the entry price of $300 is extremely fair. Thanks for reading!

Pros: Good bass response, good treble response, quick decay, detailed soundstage.
Cons: Some vocals can sound distant (<10%)
Mild ear canal fatigue after hours-long listening sessions.
The long and short is that these IEMs are amazing!

A disclaimer first: This is my first venture into High-End IEMs, and I'm coming from Bluetooth PowerBeats3 buds.

Music I Listen To: Bassnectar, Florence and the Machine, The Lumineers, Slipknot, Eminem, Shakey Graves, Apes of the State.

Device I'm using to power these IEMs: Samsung Galaxy S8 (Qualcomm variant) without a DAC.

Alright, now that you have a "floor" of my setup and experience, let's jump in! I spent two weeks obsessively researching IEMs. I started looking at cheap ones from Anker that were Bluetooth. After reading up on them and realizing that Bluetooth isn't going to be 100% reliable, I gave up the heavy desire for wireless headphones.

The next phase of this story is a doozy: I almost regretted venturing into wired IEM territory because EVERYONE has a different opinion about every IEM! Being someone that appreciates quality and wanted to invest in such, I found it hard to get a grasp on the review market.

What turned me on to the IO was that it was a moderately affordable IEM that was made locally in Portland, OR, where I live. What turned me off, were the endless bashings of that mid-frequency dip that the IO had. I couldn't justify the price of the Polaris v2, so I started looking at other IEMs. The appeal of the IO (glamour included, these are sexy) ultimately won me over.

In general, I like to think of myself as a basshead. So when people said these were clean and tight but light on the bass, it didn't make sense. After giving them a listen, they are perfect. They don't rattle my eardrums, but I can hear/slightly feel the rumble from basslines in music like Bassnectar or Slipknot. The key thing for me here is what I think people call sound stage. I could pick out instruments in the very aggressive mashing of Slipknot. I could hear instruments trading off the left and right channels. I could hear the vocals above the instruments.

Let's talk vocals for a second, because that is part of the range where this "dramatic dip" in the frequency response is occurring. Yes, there are moments where vocals sound faint (especially female), but the dip in response adds a bit of dramatic effect in my opinion. I like it! There is some sibilance with artists like Florence and the Machine, but it isn't piercing, and it is quickly rectified.

The highs were another complaint I heard about. While I am a basshead, I have a vast appreciation for detail in the mids and highs. The pop of the snare, the glitter of cymbals, the oscillation of a voice in the high octaves. It all adds to the dramatic effect of music. And these IEMs present well in that regard.

I am using the foam tips (size smaller than were mounted upon arrival), and while I do get some ear canal fatigue (especially with the advent of coronavirus and listening to music/meetings much more often), I can adjust the positioning and carry on. The weight of the IEMs isn't noticeable, though they feel very solid in the hand. The cable is awesome, the connector is reinforced, and all the bags and accessories that come with the IEMs seal the deal. I use these at home, on the commuter train, and walking around town. Isolation is great on the train and at home, but walking around I can hear my foot steps.

If you want to support local, appreciate detail in music, and like bass, but don't need a brain rattler, get the IO!

Thank you for an honest review. For us mere mortal folk gear gets dissected far to much.
Just trust your ears on what sounds good and yes I am a fan of the IO's at there price point.
I’ve been running these on an iPhone 8 with a Fiio irc mmcx cable and Comply isolation 500 tips. Using the Neutron player app, I have the IO’s eq’d as follows:
177hz +1.4
210hz +1.4
1.7hz -3.5
4hz -2.5
11.3hz -3.65

with this arrangement and eq, to my ears, they sound really good.
Pros: Fun, smooth, and analytical sound
-Great set of accessories
-Andromeda-like signature with 3D staging
-High price-performance ratio
Cons: Not meant for those who seek highly unaltered, raw presentation
-Timbre has slight coloration

Campfire Audio IO Review: Little Andromeda

It would be most likely that you have heard about Campfire Audio if looking for good earphones or IEMs - most likely the Andromeda. Though the price tag on those is not so wallet-friendly, yes? Most of the popular Campfire IEMs were quite heavily shifted to the top tier flagship models like Andromeda and Vega, which they have also started to focus on entry models.

We previously covered the youngest sibling from the Campfire family, the Comet. While Comet achieves high cost-effectiveness and usability, Campfire launched an upper model, IO, for those who are willing to get a little more serious about music. IO is also the successor of Nova which is now discontinued. It is now time to jump into the review and see how IO sounds and performs against Nova.



Campfire Audio finally went through some revamp with their packaging and I am happy about it. There are lots that do not pay much attention (or not at all), which is very reasonable. But I believe better packaging and boxing do matter when talking about premium IEMs. The size of the new packaging still goes for a reasonably small box but roughly twice the bigger than the old ones. Once you remove the CA sticker on the rear of the box, the outer packaging would unfold and reveal the inner box which includes all the belongings. I very much enjoy this new packaging as they are beautifully designed inside out and gives a feeling as if you are unboxing a present.

Other than the earpieces, it includes 1 set of 3.5mm stock cable, 1 leather case, 3 pairs of earpiece pouch, 5 pairs of Final Audio eartips, 3 pairs of CA eartips, 3 pairs of CA foam tips, 1 CA Lapel pin, and a cleaning tool. CA used to provide only 1 pair of earpiece pouch before, but it seems like they have realized the demand for it and started to throw in an extra 2 pairs - which I appreciate a lot. The lather case is also newly designed to have the same color as the earpiece. The size also got slightly larger for better convenience when storing with custom cables.



As shown, this "mechanical-looking" appearance has been Campfire Audio's signature design from the get-go. The earpiece is made of machined aluminum and sports an edgy look, though the edges are slightly rounded as well as the inner side forming a fairly ergonomic shape. Not the best in terms of comfort or compatibility, but the fit is not bothering at least. Though users with smaller outer ears will have problems fitting these to their ears as the earpieces are still a bit chunky and edgy.

IO uses 2BA drivers per side - each working as a woofer and a tweeter. Both drivers are incorporated with T.A.E.C. (Tuned Acoustic Expansion Chamber), which is a specifically designed inner structure that sits in front of the drivers and takes a major role in creating their signature sound. The nozzles are made of stainless steel and separated into 2 bores. Another thing to note is that the shape of the nozzle has changed. The nozzles are visibly longer than the old ones which give deeper fit and better isolation. The earpieces are detachable and use custom-made MMCX sockets that are compatible with typical ones yet inforced in durability.



The stock 3.5mm cable went through some changes too. First the shielding. The previous silver-plated Litz cable had a transparent silver look which looked good, but vulnerable to discoloration and stains. The new version has a smoky grey jacket that solves such problems as well as being even softer. Metal memory wires are gone too and replaced with a simple ear hook design.


Sound impression - Ultra lows / Sub-bass

IO shows a mildly w-shaped sound signature with a small emphasis on the mids. Ultra lows are mediocre, but it manages to deliver enough depth and weight to the sound. Considerably good for a 2BA setup. Bass shows a meaty and high-density thud, striking fast and decaying relatively slower which makes the lows feel full and natural without lagging behind the beat. While the bass creates quite a deep and dark atmosphere, the area for spreading the bass reverbs is well controlled and energetic without getting loosen.

Reverbs are soft and relaxed, resulting in the overall bass quantity to be similar to most IEMs with a slightly v-shaped signature. It is somewhat easy for full BA IEMs (especially those with fewer drivers) to sound dry or lack liveliness, but IO's bass show much liveliness and moisture like a tightly controlled dynamic driver. Overall the bass is up to par with the quality, even without regarding the driver setup. Not to a game-changing degree, but most people would be able to easily enjoy in both quantity and quality.


Sound impression - Mids / Imaging

The thickness on the mids is just around neutral and works well with both male and female vocals. Comparative to lows and highs, mids put more weight on the airiness rather than density. Not only this presentation blows in lots of air into the sound, but it also allows vocals to sound more spatial and stable. Since that, IO keeps the vocals quite flat and very stable throughout the midrange without noticeable dips, spikes, or sibilances. IO's sound is extra sensitive to the fitting, so I suggest trying a variety of eartips as the sound may cause hollowness or spikes if your fitting is not secured enough.

Another characteristic of IO is its positional aspect. While we use terms as close/neutral/laid back for explaining the relative position of the vocals, though vocals on IO feel as if they are spreading out from more of the rear side which eventually reaches out to the front. This creates a spatial, lively presentation that keeps the vocals absolutely fatigue-free. Thanks to these two characteristics, delicate reverbs and airiness, IO's mids do not feel stuffy despite the overall brightness slightly tipping over to the darker side.

Therefore, those who dig 3D effects or the ones that are used to multi-driver-ish sound should find IO's presentation quite pleasing. However, those that are extra sensitive or demand raw/original presentation may find it bothering - especially if you do not like the sounds from full-BA or hybrid IEMs. If you are used to IEM-generated staging, it is likely not a problem. Although I am pretty sensitive to artificial sound, I found the presentation to be fun as it is not like the timbre has been completely abandoned or completely went over the head.


Sound impression - Highs / etc.

Highs are another part that supplements some freshness and shine to the sound while keeping the sound comfy and relatively dark. Highs are crisp and analytical, being capable of grasping the small sparkles and layering clearly separated from each other. The lower trebles take a slight dip and then continues to shine - this will not kill the treble details but rather prevents the highs from getting overpowered or harsh. The thickness is on the slimmer side but has enough body to it. Highs also have a super-fast response speed and don't leave many reverbs or residues, keeping the atmosphere clean and organized. I am in fact very pleased to see such detailed and crisp treble quality for a 2BA IEM in this price range. It feels solid and high in clarity without getting too close in the face or feeling rigid. Highs make sure to keep its presence clear and prominent, with a lively and tasty timbre but not to the point of falling behind in neutrality.

Staging is quite on the larger side - not gigantic, but to say the least, the 2BA setup does not seem to be limiting IO from presenting a dynamic, wide, and full headroom. It is important to point out that this presentation is formed with accuracy, so the wider staging was not achieved by throwing in a bunch of resonance. IO shows just the appropriate amount of resonance to blow in musicality and smooth flow to the sound while maintaining a clean enough background. Imaging is also correctly presented, doing a fine job locating the instruments to their intended places.


Compared to Nova (2BA)

I always had a soft spot for Nova. Its smooth and fatigue-free sound was its charm that I also appreciated, yet it has not gained much attention from the users and got discontinued fast. Anywho, IO is Nova's new successor so this would be a good comparison. Nova presented a rather slow-tempo, old-school sound, while IO is up for a more engaging and trendier sound reinforced with vibrancy and brightness.

IO also presents mids in a more uplifting, refreshing, and airy manner. The resonances are slightly lesser than Nova yet IO preserves plenty amount of reverbs and quantity, making the sound just full as Nova but even better in clarity. Though Nova would not be put down to the grave since it still holds its ground with its own charm. Nova is still very desirable for those who dig a Westone-like sound signature with a harder bass texture, but if you are looking for more upper frequency details and sparkles, IO would definitely be a superior choice.

Eartip / Cable suggestions

Recommended eartips for IO would be either Final E-Type (the ones included as accessories) or Acoustune AET07. This would be more about personal preference, though I would suggest AET07 eartips as the best matching as it provides a wider, unaltered sound presentation. It is also crispier and higher in transparency, so the upper frequency details would be opened up even more. The bass still keeps its tightness with a good amount of quantity. E-type eartips would be a better deal if you want the sound darker or bassier, though unless that I would suggest giving a try with the AET08. The best cable selection with an affordable price would be Satin Audio Gaia and I am confident about it. Satin Audio has been recommending the IO-Gaia combo even before I got my IO in hands, and those two sure do match well. Gaia provides better clarity, staging, and tone throughout the sound as well as delivering a richer bass response.



I have seen some mixed impressions for IO, yet my experience has been positive all the way since the first time meeting this IEM during an exhibition. Campfire Audio has done a good job boiling down the Andromeda into a 2BA version, forming an exciting sound signature yet consisting of enough neutrality. Not ideal for those desiring the most plain or unaltered sound, but for a fun, toned up fidelity gear, I would say this is one of the fairest choices you could make. Built upon Campfire's signature sound, IO is a cost-effective performer that I would actively recommend as it holds a powerful, hackish place in the lineup. Keep your eyes over here if you are looking for a sub $300 IEM with an all-rounder, fun sound signature.


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Thanks to CA for providing IO for an honest feedback/review.
I am not affiliated with CA and none of my words were modded or asked to be changed.
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Watermelon Boi
Watermelon Boi
The pics always make me wanna buy whatever your reviewing haha
Watermelon Boi
Watermelon Boi
Pros: Fun and dynamic sound
Eye-catching color choice
Competitive pricing
Cons: Shell is still vulnerable to scratches
Soundstage could be wider
Highs might be harsh for some users
With much effort, innovation, and creativity, Campfire Audio launches their new midrange in-ear monitor (IEM) IO, redefining the category benchmark.

This post is originally posted on Headphonesty. Thanks to Jayden from ConnectIT and Campfire Audio for sending the Campfire Audio IO. The product was provided to me free of charge in exchange for my honest review and opinion.

Campfire Audio announced the launch of two new models, Campfire Audio IO and Campfire Audio Polaris V2 during Fujiya Avic Headphone Festival 2019. After the launch in Japan, I had the opportunity to work with a distributor to launch these two models in Singapore. This has been an amazing experience for me because of the support from the Campfire Audio fans.

I have been impressed by Campfire Audio since the first launch of Orion, Jupiter, and Lyra. To me, the new Campfire Audio IO is a replacement for the previous dual balanced armature model, Nova. I have been using Nova for almost three years and it has served me well.

Is it an adequate replacement? Absolutely. Read on to find out why.

Spot me in the photo!

Campfire Audio IO

The packaging for Campfire Audio is like a child, growing with each new release. Look how big you’ve gotten!

I compared the new packaging with my original generation packaging from Campfire Audio Nova and the differences are significant. The new packaging is more grand and classy compared to the simpler old packaging.

Campfire Audio changed their design approach for the box and IEMs - mainly on the color theme. Now, the box, case, and IEMs have the same color. You can immediately identify the models from afar based on either the box, case, or the shell color. The palette of choice for IO is red.

The outer layer of the packaging is a sleeve with a sticker depicting the IEMs, model, and brand. The sleeve can be opened up by removing the small round sticker at the back of the sleeve

An eye-catching red package.

Box color matches the IO shell color.

After opening the sleeve, the presentation of the inner box is amazing. The inner box “shines” like a galaxy and is the central focus of your attention. Words cannot describe its beauty.

Opening the sleeve.

The inner case.

Campfire Audio logo on the inside of the sleeve.

Opening the inner box, you will find a red leather case with the IO sitting inside. The case is a major change--it looks like a red curry puff (I like this description, it is from one of my co-workers). I like the new case. It is more spacious compared to the previous squarish case.

The red curry puff

The actual curry puff

There is actually an underlying reason behind this specific case design - to give back to society. According to Jayden, the case is crafted by a handicapped case manufacturer and Campfire Audio uses his case to support him.

Besides the case, you will find an accessory box. These are the accessories in the box:
All these accessories are kept in a Campfire Audio mesh IEM bag. This could be useful for storing your IEMs and preventing them from being scratched.

Campfire Audio mesh IEM bag

Technical Specifications
  • 5Hz–22kHz Frequency Response
  • 109 dB SPL/mW Sensitivity @ 1kHz
  • 26 Ohms @ 1kHz Impedance
  • Dual Balanced Armature Driver Design.
  • Newly Insulated Custom Beryllium / Copper MMCX Connections
  • ‘Garnet’ Red Anodized Aluminum Body
  • 24k Gold Plated Screws
  • Stainless Steel Spout
The IO features a ’Garnet’ Red anodized finish with 24k gold plated screws on a machined aluminum body. The color is very eye-catching. The color scheme looks like Iron Man and the IO launch date was coincidentally close to the Avengers : End Game onscreen date. I fell in love with it on first-sight - simply lovely.

The anodized body is claimed to have better scratch resistance. Campfire Audio fans have always faced this issue - IEMs with a lot of scratches. Within 2 months of usage, I noticed some scratches on the shell, but this is mild compared to older models like Andromeda.

Close look at Campfire Audio IO.

Besides the improvements in the shell, Campfire Audio also improved the MMCX port. A custom beryllium-copper insulated round MMCX connector is featured on the IEMs. Tested and proven, the MMCX connector gives me a satisfactory “click” whenever I attach the cable.

Round MMCX port is found on top of the shell.

Comparison between IO and Nova MMCX ports.

The IO has a stainless steel spout or nozzle which improves its durability. As I mentioned in my previous review for Simgot EK3, the connector and the nozzle are the weakest points on IEMs. The IO’s implementation successfully improves the overall build quality.

The cable included in the case is the new Smoky Litz Cable. Built from ALO Audio Silver Plated Copper Litz wire conductors and tangle-resistant twisted cable weave from Silver Litz and Super Litz cable, Campfire Audio added a new stylish Smoky jacket to compliment the unique finish of their new line of earphones.

Smoky Litz cable has a new light-weight molded ear-hook design that replaces the memory wire in previous cables. The result is a lightweight cable that is a pleasure to use every day.

This could be great news for audiophiles who are wearing spectacles, like myself. Memory wire ear-hook designs are disastrous for us. For those cables with memory wire ear-hooks, the memory wire constantly hits our spectacles when we are moving. This creates a “microphonics-like” noise. Besides the noise, it is hard for us to shape the ear-hook due to the presence of spectacles. The new cable saves us from this microphonic hell.

New smoky litz cable

Fit and Isolation
IO has the typical shell shape we’ve seen with previous releases from Campfire Audio. There are some slight changes, namely weight and edges. Due to the change in material, the new shell is lighter in weight compared to the previous releases. There are fewer sharp edges in IO and this yields a more comfortable fitting. I can wear IO for hours without an issue.

The isolation for IO is above average. When commuting, I can immerse myself in the music by turning the volume only slightly higher when compared to normal listening.

For this review, I paired the Campfire Audio IO with my daily Digital Audio Player (DAP) - Opus #3. I used Symbio ear tips by MandarinEs for this review.

Campfire Audio IO paired with Opus #3.

IO is an exciting and exceptionally expressive earphone. The sonic performance stands with our best work to date. It has an excellent vocal presence. There is a splashy energy to its musical delivery that I think many people will enjoy. - Ken Ball

IO is a fun sounding IEM. Utilizing a woofer and a tweeter, the high and low frequency regions are fully covered. This results in a slightly “U” shape sound signature. This was a wise tuning choice because it has the potential to be the most well-received sound signature within the price range of USD$300.

The soundstage of IO is slightly below average. I find the overall presentation to be relatively forward compared to other models from Campfire Audio. I have very high expectations for staging, however, and there is some slight disappointment here. Happily, this is not a deal breaker. Compared to other brands, the soundstage is still good.

IO can be easily driven. I tested it with my iPhone and I get a good audible level without crossing 50% of the volume. This makes IO a good choice for those beginners with no powerful DAPs or amplifiers. Good approach by Campfire Audio.

As a Campfire Audio Nova user, the lows performance of IO actually reminds me of Nova. The presentation is pretty close. As a pure BA driver IEM, the lows dig considerably deep. The attack and decay speed of the lows is fast and precise. No redundancy in the response. I really appreciate this because bleeding of lows into mids, and the resulting slow response, is a big taboo for me.

Lows that are too fast may result in an overly analytical response. Campfire Audio knows this and they found a good balance between analytical and muddy, resulting in a warm and fun sounding IEM. This could be a unique selling point on its own, but I think this is not the only one. We will explore more.

Campfire Audio lineup.

This is the critical part. No BA driver is dedicated solely to the mids in IO. So, are the mids weak? My answer to this question is no. Being a mids lover, I actually love the presentation of the IO. The mids are slightly recessed, staged below the lows and highs. Despite being slightly recessed, the vocals still sound airy and clear. The mids have a great space to expand due to the tuning. This results in very breathy and spacious mids.

Why do I say this part is critical? If you read the thread on Head-Fi, you will realise there are very controversial comments on this frequency spectrum. I believe Andromeda users might find the mids muddy but we should understand that the price difference between the two IEMs is huge and this comparison is unfair towards IO. I believe IO can serve certain groups of audiophiles well.

Is IO a good replacement for the Nova? I think it is.

With the Tuned Acoustic Expansion Chamber (TAEC) implementation in the BA driver, highs are not an issue for IO. They are well extended with a sufficient amount of air. Highs have never been an issue for Campfire Audio except for Nova where the highs rolled-off too early.

The well-extended highs improve the overall fidelity of the presentation.Thanks to the highs, the overall sound signature is prevented from being too warm.

Are the highs sharp and peaky? This is a tricky question for me to answer because I have a very good tolerance for treble. I would answer no. The highs are gentle enough on my eardrums. No harshness and no piercing even after long listening.

Father and son.

The Campfire Audio IO is a great choice for audiophiles who are looking for a mid-tier IEM with fun and dynamic sound. IO can save your pocketbook from becoming too light for sure. This release proves that Campfire Audio is continuously improving and we should continue to pay close attention to their new releases.

IO retails for USD $299. It can be purchased from the official Campfire Audio website. For those residing in Singapore, you can drop by ConnectIT by Jade Gift Shop to make a purchase.

Outstanding performance from IO makes it a good replacement for the now obsolete Nova.
Pros: Fit is excellent
Case and Cable are improved upon greatly
Treble is decent for a warm tuning
Included accessories are best in its class
Cons: Midrange is tuned strangely
Bass has slow decay, blunt attack
Has a "hazy sound" across pretty much the entire frequency response

Disclaimer: the Io was given to me for review by the HEADPHONE Community Forum

The Campfire Audio Io is, at least to me, a black sheep out of what some would already consider the black sheep of the IEM world. Even for the brand, the Io was getting lots of attention for its supposedly odd tuning. I was especially interested because on Discord, Antdroid said the Io’s bass and treble were overall an improvement over its predecessor, the Orion’s. Having tried the Orion, the Io had me crossing my fingers that it could be like a ‘fixed’ version of it with better bass, and more importantly, treble extension in the realm of acceptable. I knew about the odd tuning and measurements floating around, but even then, I went in with above average expectations because Resolve Reviews stated that without considering measurements or any other reviews, the Io was a strong contender. So, after finally hearing the thing myself, I have to say I’m heavily disappointed by it. I say “heavily” because while the tuning is essentially the opposite of my preference, the Io has improved from the Orion in some regards that I have to commend it for. However, at the end of the day, I vastly prefer the Orion to it despite being lukewarm on it, and the Io comes off as something that I would be unable to confidently recommend to anyone.

Accessories, Tips, and Other Less Important Things

Much like the Orion, the Io comes with a plethora of accessories, with a new case and cable to boot. I stuck with the Final Type E tips like with the Orion, and with the new nozzle on the familiar shell, the Io is one of the more comfortable IEMs I’ve worn. To add even more points to the overall ergonomics, Campfire finally did away with the Silver Litz Cable in exchange for a more non-bad Smoky Litz cable, with a better general feel and finally no memory wire. The premolded earhooks combined with the deeper fit makes putting the Io in dead simple, which would incline me to use it more often than my beloved ER2SE (that is, if I enjoyed the sound). Furthermore, the Io handles different sources like a champ, something the Orion just plain could not do. And on top of that, to add on to what is essentially a perfect fit and pairability, the Io looks damn amazing too. I said I loved how the Orion looked, and I still do, but the Io takes that and goes all the way with it. The ‘regular coating’ does the red color more justice than the Cerakote does for the Orion, and the gold screws are really striking in contrast with the housing. Sorry for the rant about the looks, but I just want to reiterate that the looks and fit are so great that even if this sounded just mediocre, I might have even wanted one for myself. Finally, before the meat of the review, let me disclaim that testing was done over the course of a week out of a Hiby R3 and Pixel 3a.

General Sound

As a whole, the Io sounds just simply “off.” Like Resolve said, the Io’s flaws could be easily ignored with enough effort, but I personally believe that most things can be brushed off if you don’t have anything to A/B, or if it’s your entry into the hobby (maybe that’s why things like Grado or Audioquest get so much praise). The fact of the matter is that the Io is strange hearing it alone, but then once you try something with a normal tuning, it becomes just plain absurd. I’ll go more into detail when talking about frequency response and the songs I used to put the Io to the test, but going back to IEMs I use as daily drivers just exemplifies how the Io falls completely flat in the presence department (and more!) While the ER2SE is engaging and technically impressive to boot, the Io is just not memorable to me at all. I honestly feel like Campfire went one step forward, ten steps backwards in regards to the Io succeeding the Orion. While the Orion suffered from poor extension, it was otherwise a safe tuning with engaging vocal performance. The Io, on the other hand, fixes any ergonomic issues I had with the Orion, along with the extension while having a butchered tuning. Anyways, I’ve vaguely hated on the thing enough, I’ll give further reasoning in the following sections.


I agree that the Io’s bass extension is an improvement from the Orion — enough so to make listening to electronic music feasible, a genre that inclined me to reach for the GR07 Classic over the Orion. However, when listening to rock music, most of the time the Io’s bass did not do any of the songs I listened to justice. The bass has a blunted attack and sounds mushy overall. It’s not really a limitation of the BA either, because balanced armatures are generally known for their quick bass attack and decay.


I am unapologetically a mids-head, which is why I’m inclined to be even more critical of the Io’s midrange than others might choose to be. The Io, for some inexplicable reason, has a ‘unique’ peak in between 1.5 and 2kHz that I legitimately cannot explain. The most instant consequence of this peak is that all vocals lack presence, which might not be immediately egregious, until you switch to something with a more traditional tuning. A/Bing with the ER2SE did not do the Io any favors, especially considering that I personally prefer a bit of a 3kHz bump, which the Io has essentially the opposite of. Additionally, my favorite genre is rock music, which again, the Io does not do any favors. I say this because, and this is my main complaint, the Io reproduces guitar in a way that sounds muffled to the point that my mind is boggled as to how the tuning was decided on. Needless to say, Campfire really dropped the ball on this one (pun intended).


To me, the treble is the best part about the Io. It extends much better than the Orion, and doesn’t have any egregious flaws like the aforementioned segments. However, my only complaint comes completely down to personal preference. The treble on the Io is a bit warm for my tastes, and that’s totally ok, I just prefer my IEMs’ treble to be neutral or a bit brighter than neutral is all. Otherwise, for better or for worse, I don’t have much else to say about the Io’s treble.

Song Test

This might be the part where I lose what little credibility that I had, but rather than force myself to listen to Hotel California or Random Access Memories, I prefer to just test with songs I listen to often.

Women - Eyesore

This song was interesting to me because I have to thank the Io for helping me appreciate it more. After listening to it, the hazy production and vocal effects seem like they aren’t being affected by the Io’s inherent haziness as much, but going back to my other IEMs, I realized how much presence the singer’s vocals have in the song. Doesn’t help that the guitars sound artificial though...

Neutral Milk Hotel - Holland, 1945

Similar to how I critiqued the Orion for sounding cluttered with this song, I think the Io does a much, much worse job of handling the distorted guitars than its predecessor. Again, the guitars sound distant and flat, but this is much more of a detriment with this song than it was with “Eyesore” because it makes the whole instrumental just melt into a messy mixture of sound that takes nearly all the nuance out of the song. Yikes.


I will give the Io credit on this one, I legitimately enjoyed this song with them in. The bass didn’t bother me as much, although it was still a bit slow sounding, but honestly I didn’t have much to fault. The Io’s treble and decent bass extension kept this song exciting the whole way through.

King Gizzard & The Wizard Lizard - Self-Immolate

I decided to throw some metal at the Io, and unfortunately, the guitars still sound hazy, but less so than usual, with drum kicks also failing to satisfy. Vocals didn’t sound too bad though.


The Io is not very good, I’ll admit it. It’s a damn shame too, because the looks and fit of the Io were both some of the best I’ve experienced. It’s just a shame that it didn’t really play out sound wise. Unlike the Orion, which I consider a mediocre all-rounder plagued with poor extension that some could ignore, I cannot in good faith recommend the Io to anyone looking to break into the $300 range. Having tried the trinity of Campfire Audio entry level models, the Comet, Orion, and Io, I can confidently say that they are not worth your time when other, stronger performing options exist for less than half the price of any of the trio. For example, in the realm of balanced armatures, the FiiO FA1 handily outclasses all three of them at $99. However, unlike the Comet and Orion, I would go as far as to say the Io is a failed experiment. If the Orion was, say, a 5.5/10, I would have no problem putting the Io somewhere in the realm of a 2/10 at the very least for not just my genre and midrange preferences, but I simply wouldn’t recommend it to anyone due to the general haziness and guitar muffledness. It’s hard to remind myself these are $300, but at that price, I would not buy these. At $100, I would not buy these. I’m sorry to be so harsh on the thing, but it was a huge disappointment to me. At the very least, I would only consider the Io if you had something else that was considered ‘good value’ for $300 side by side with it to compare. To blind buy these would be insanely risky for that midrange peak alone.


I was disappointed too.
IO sound worse than most of the iem I have heard.

I can get Panasonic ergo fit and invest in stock market rather than buying IO

It was so bad for me
Pros: Build quality; Cable
Unique design
Detailed sound; suited for vocal (female) oriented genres
Cons: Sharp design may present comfort issues
Very specific tuning missing balance
Review – Campfire Audio IO

Website – Campfire Audio


  • 5Hz–22kHz Frequency Response
  • 109 dB SPL/mW Sensitivity @ 1k
  • 26 Ohms @ 1kHz Impedance
  • Dual Balanced Armature Driver Design.
  • Beryllium / Copper MMCX Connections
  • ‘Garnet’ Red Anodized Aluminum Body
  • 24k Gold Plated Screws
  • Stainless Steel Spout

Price: U$299.

Official IO page.

Credits to Campfire Audio for kindly arranging the IO unit for review.

The package and design description have been already covered on the Polaris 2 review, and being almost identical it will just rephrased accordingly to the own IO characteristics.

As part of the new Campfire Audio earphones versions, the IO also arrive in the fresh new designed box. A very compact and light cardboard box with a corresponding color them to match the product colors and scattered sparkles to give that galactic theme look.

The package inside is tightly organized with a new set of accessories. The earphones arrive inside a leather like case, and in the case of the IO, in striking garnet red color. Admittedly, the new case looks more like a small lady purse than won’t be easily overlooked as with usual standard cases; a new touch from Campfire Audio that may not suit everyone. The smaller rectangular box holds two sets of dual mesh pouches with various sets of ear tips. There are five sets of final E silicone tips, three pairs of standard tips of wide bore and three memory foam tips. The wide tips do not fit well to the IO, the core is too wide to attach well to the earphone spout. There is also a cleaning tool, and of course, the little Campfire Audio pin.


As usual for Campfire Audio earphones they combine a strong build quality with very eye-catching design. The shells main body is made by tough anodized machined aluminum material painted in garnet red color, resulting in a beautiful metallic matte finish. Even though, the paint may get off after some short time, especially with the various sharp corners on the shells; using the dual mesh bags is recommended to avoid unnecessary scratches when storing and carrying the earphones. The earpieces consist of two outer and inner parts strongly attached by the shining metal gold plated screws, giving an even fancier look to them. The nozzle is now stainless steel. There are no bores on the nozzle but instead small grills. Despite the all metal design, the shells remain light and comfortable to use. Being an all BA unit, the shells are completely sealed; however, isolation is just about above average. It is still noticeable better than the Polaris 2 which has a small vent for the hybrid setup, and there is no wind noise with the IO.

The shape is the typical one for many of the Campfire Audio line that while being very unique has many sharp corners. The fit is still easy for a strict over-ear wearing IEM. The right position should be with the ‘CA’ logo horizontally lined. However, these are not small shells and the sharp design can be uncomfortable. Even so, with the slim and longer nozzle it is possible to achieve a less obtrusive fit with less contact to the outer ear skin. Not going to win in terms of comfort but can still be used all day long.

For the detachable cable connection the IO features the newer MMCX copper coated sockets introduced on these last models. The cable is also a new model from the company. A standard braided four strands cable made of silver-plated litz wires. The MMCX plugs are beryllium coated and they safely attach to the earphones. There are fixed ear guides over the previous memory wire used but they are very soft to be even noticed.

Sound Quality

Shanling M5s, HiBy R6 Pro, iBasso DX220 (Amp1 Mk2), FiiO M6.

Some IEMs used for comparison: iBasso IT04 & IT01s, Brainwavz B400, Fibae 3, final E4000, FLC 8N, Symphonium Audio Aurora (Sonion dual BA).

The IO has a very specific tuning. Not to be called unique or special, just specific, and maybe too much. Overall the sound is smooth and liquid, with a very strong lift on the upper midrange and low treble. The signature does not aim for a true balance and it is certainly not neutral either. The IO shows the typical characteristics of balanced armature drivers, their strong points and also weakness.

Despite the large woofer BA driver used on the IO, the low-end is very soft and polite. Very neutral at best and for many listeners might be found too light and with not enough impact on the bass. Sub-bass is limited and rolled-off. Mid-bass is more present; again, bland sounding. However, there is quality on the IO; it is tight and very controlled, and for a very linear bass response there is good layering and separation. Speed is also very good, typical for a balanced armature and better than the Brainwavz B400 (Quad BA) and Aurora (Dual BA - Sonion).

The smaller armature unit is in charge for the midrange and highs. Lower midrange is thin and lacks weight, following a similar presence as the bass. As such, it is detailed and clean without sense of warmth, making male vocals sounding a bit more recessed. The gain starts on the upper midrange which gets a strong boost and forwardness over the whole presentation. It breaks the whole balance, putting upper instruments forward and female voices even more prominent; not particularly too sweet, but yes very detailed. There is lot of energy here yet very good control and very little sibilance that can be perceived at moderate volumes. Upper instruments can get a bit exaggerated giving a less coherent timbre. The gain continues to the lower treble; rather than having a certain peak it is more about a whole elevation at these frequencies. Afterwards, the treble goes down with a slight roll-off up the upper highs. Not as limited in extension as the bass, though. The IO is not a really bright IEM; there is not a hot treble or too aggressive and the control is well achieved for this price. The soundstage is expected limited though the resolution is quite good.

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Good reading!! :) It's always a pity when Andromeda's shape like IEMs doesn't fit ears... Did you have a chance to own/listen to the CA Orions for a brief comparison? :)
Thank you! The design is really cool, but still would like to see a smoother, better rounded shape.
Sorry, this IO and the new Polaris are the only CA IEM I've tried so far.
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I got your point. Maybe the next CA CNC manufacturing process will allow such shape. You are not the only one who will appreciate it :)
Pros: Build quality - Accessory kit - Bass quality - Texture and detail
Cons: Fatiguingly bright - Not a very natural presentation - Inconsistent mid-range

Today we're checking out the new IO (Eye-Oh) from Campfire Audio.

Campfire Audio is located in Portland, Oregon and was founded in 2015 by Ken Ball of ALO Audio fame. In the world of high end portable audio they rapidly became a household name thanks to the Andromeda with it's iconic design language and impressive performance.

The IO that we're checking out today is one of their newest releases. Along with all-new packaging for the brand, it features a dual armature setup and the same angular design that is shared with many models in their lineup, and that won them great accolades from the community when they first appeared on the scene.

As one of their most affordable models, is the IO a worthy addition to Campfire's lineup? Let's find out.


Thanks to Caleb with Campfire Audio for arranging a sample of the IO for the purposes of review. The thoughts within this review are my own subjective opinions based on time spent listening to the IO throughout the last two months. They do not represent Campfire Audio or any other entity. At the time of writing the IO retailed for 299 USD. You can check it out here:

Personal Preference:

I listen primarily to various EDM sub-genres (liquid drum and bass, breakbeat, drumstep, etc.), hip hop, and classic rock. My preferences for earphone tuning are quite relaxed and as such their is no one signature I look for. The HiFiMAN RE800, Brainwavz B400, and Massdrop x MeeAudio Planamic are examples of earphones with wildly varied signatures that are enjoyable for different reasons. I generally listen at very low volumes, so keep this in mind when perusing my thoughts on how an earphone sounds.


Mobile: Shanling M0 alone or with the Periodic Audio Ni amp, ZiShan DSD
@home: TEAC HA-501 with a ZiShan DSD or Asus FX53V acting source duty

The IO is very easy to drive and doesn't need to be amped. A phone drives it just fine. That said, since it is somewhat bright and quite revealing, it sounds best out of a clean, warm source so I do recommend a decent DAP or DAP/amp combo.

  • Driver: Dual balanced armature
  • Impedance: 26 ohms
  • Sensitivity: 109dB
  • Frequency Response: 5Hz to 22kHz
Packaging and Accessories:

When it comes to packaging, Campfire Audio has changed things up this time around. The spirit of their past designs is still in place as they follow the same astronomical theme, but the format has changed. Similar to the Solaris, the IO comes in a fairly large, shallow square box. Unlike with the Solaris, this box is covered by an exterior sheath, sealed shut by a gold coloured Campfire Audio seal on the back. The front contains a large sticker with a mottled pattern set beneath a high quality image of the IO's earpieces and the usual company branding and model information. One more sticker is present around the side containing company info and another image of the IO, among other details that may or may not be important to the average consumer.

Breaking the seal, the sheath unfold like the pedals of a flower revealing the main box inside. Lifting out the box, you will notice the inner sheath is printed with the CA logo dead centre, golden rays exploding outwards. It's quite dramatic. The main box itself contains the same beautiful mountainous scene found on CA's prior packaging along with more Campfire Audio branding. Lifting the lid you're greeted by the slogan “Nicely Done” printed on one of the flaps, as well as their new leather carrying case and a smaller cardboard box containing many of the included accessories. Beneath all this is your warranty card and a manual. In all you get:
  • IO earphones
  • Smoky Jacket Silver Plated Copper Litz Cable
  • Final Audio tips (xs/s/m/l/xl)
    Campfire Audio Marshmallow tips (s/m/l)
  • Wire bore single flange silicone tips (s/m/l)
  • Campfire Audio lapel pin
  • Cleaning tool
  • Mesh accessory case (x3)
Overall this is an outstanding unboxing experience, as is always the case with Campfire Audio. But...I still prefer their old packaging. It was smaller and more compact thereby using less material and producing less waste, a big plus for those that toss packaging once they get to the goods within. That said, this packaging still produces a lot less waste than what you get with various other brands (RHA, Dunu, etc.), and everything is recyclable, so take this as more of an observation than a complaint. The new box does look fantastic on display though, a positive for those of us that appreciate brands who put time and effort into crafting unique and attractive unboxing experiences.

Packaging aside, the accessory kit is second to none. Final Audio tips are some of the best in the business and with five sizes included you're sure to find something that works for your ears. Campfire Audio's Marshmallow tips are a very high quality foam option. The basic single flange silicone tips are nothing special and are the sort of tip you'd find included with more budget oriented offerings. That's not to take away from their performance though. They stay attached to the nozzle just fine and consistently seal well, though I'm not a fan of how they sound with the IO. The cleaning tool will be invaluable to those with waxy ears and the inclusion of three mesh bags to keep everything neatly organized is genius. Nicely done.

P1020811.JPG P1020812.JPG P1020814.JPG

Build, comfort, and Isolation:

The machined aluminum housings of the IO are adorned with a pale red anodized finish that looks pretty stunning in person. Seems to me that Campfire has improved the quality of their machining and their anodized finish. Compared to the original Polaris, the shells are much smoother. Small bumps and knocks that chipped the finish on the original Polaris have done nothing to the IO. ~10mm long stainless steel nozzles are present and have a prominent lip that does a great job of holding tips in place. These nozzles are very similar to those introduced with the Atlas and Comet and incorporate protective grills into the design. You won't have to worry about losing a filter when changing tips. Gold plated screws top things off and attractively accent the red colouring, Iron Man style. The IO use's Campfire Audio's now familiar and extra durable beryllium/copper MMCX connectors. I say extra durable because that's what the marketing blurb spouts, but also my now almost two year old and well-loved Polaris has seen tens and tens of disconnects. The MMCX connectors are just as firm now as they were out of the box. Fit and finish is as to be expected, which is to say it is fantastic. Seams are barely visible and everything lines up perfectly without any gaps or off kilter angles.

The IO comes with Campfire Audio's new Silver Plated Copper Litz cable. It is quite reminiscent in design and thickness to the copper cable that came with the original Polaris, but with a new smoke coloured sheath. The 90 degree angled jack is smartly designed with an extension to permit compatibility with a wide variety of device cases, though strain relief is a little stiff. Less of a worry than it would be on lesser cables. My experiences with Campfire's cables have shown them to be plenty durable. Within the small, reliefless aluminum y-split, the cable divides sending two strands on each side to the ear pieces. Slotting into the top of the split is a small plastic chin cinch. It moves much more smoothly here than on older Campfire cables and as a result is much more useful. Also much more useful is the move to preformed ear guides. While the memory wire used on past Campfire Audio cables worked, I found the “memory” aspect of that title limited at best which led to the wire straightening out over time. Ditching that entirely and running with preformed guides has resulted in a much more pleasant experience since I'm not constantly rebending the wire to ensure it stays behind my ear. This is a great new cable and I was pleased to see it included with some other new models, like the Polaris v2 and Andromeda v3.

When it comes to comfort you'd be forgiven for assuming Campfire Audio's iconic angular shell design is a pain in the ear. Maybe for some, but not for me. Ergonomics are just right with the low profile IO conforming quite naturally to my outer ear. That plus the use of lightweight aluminum, a small size that belies the chunky appearance, and a reasonably long nozzle keeps the IO sitting in a way that does not feel out of place. While I find the stubby nozzle of the Andromeda more suitable to my personal ear anatomy, I can still wear the IO for hours without experiencing any discomfort.

The passive isolation of the IO is kinda weird. Low and high frequencies are significantly dulled when I have them inserted, Final Type E tips installed. This is great. Oddly though, vocals come through loud and clear, if not slightly dulled. As a result, I can have a video on in the background at my normal listening volume, IO inserted into my ears with no music playing, and follow along with the host/commentators just fine. This is actually really handy when using the IO in an office setting where you need to be able to hear your colleagues. That is, as long as you're not using foam tips. Those tend to sop up vocals and muffle everything.

P1020817.JPG P1020818.JPG P1020819.JPG


Tips: I found wide bore tips exacerbated the mids and treble making the IO flop over the edge into being overly aggressive. Small bore tips like the included Final Audio E-Type, foams, and other small to medium bore, soft silicone tips (ex. Sony hybrids, Spintfit CP100, etc.) were preferable since they curbed some of that edginess. My testing was done with the included Final Audio medium tips.

The IO has plenty of treble on tap giving it quite a bright presentation. Hi-hats, chimes, etc. are quite vibrant and can get tiring quickly. This was noticeable on King Crimson's live recording of “Indiscipline” off the 'On Broadway' collection. In the first couple minutes the drummer gets to show off his skills and you are assaulted by a barrage of hi-hats. On the plus side, notes are fairly well-controlled with a satisfactory amount of space and air present. This keeps the IO from coming across congested and muddied when a song get busy. Attack and decay are expectedly quick, but not so snappy as to sound unrealistic. Detail and clarity are quite good too and I never felt I was missing out on any fine details, or that the IO was smoothing over imperfections. It sounds quite unforgiving and quite revealing actually.

Vocal presence in the mid-range is somewhat inconsistent. On some tracks, like Tom Walker's “Now You're Gone”, both male and female vocalists sound forward and prominent with neither standing out more than the other. Other times, like on Radiohead's “Weird Fishes”, vocals fall back and sound recessed in comparison to the bassline and high hats, especially in the closing moments. This really only happens with male vocalists and it varies from track to track. The IO certainly feels most at home with female vocalists though. I was somewhat surprised with the IO since it handled Nicki Minaj well. Many earphones with unique mid-range presentations tend to make her sound very nasal, but that isn't the case here. Running through “Ganja Burn”, her vocals are smooth and sweet, blending in perfectly with the simple instrumentals and background accents. When it comes to guitars and other instruments, timbre is too light but I otherwise enjoy the presentation. Take for example, Havok's “Covering Fire”. Riffs chug away with a sublime attack and wicked texture. Pianos fall much into the same realm, as heard on the 51 second piano solo opening Supertramp's “Bloody Well Right”. While the piano doesn't sound quite right, it still manages to be entertaining and serve its purpose of pulling you into the track to preparing you for the eventual crescendo. The IO's mid presentation is off, yet it didn't manage to ruin the immersion of a good track, even one I've listened to as much as “Bloody Well Right”.

The IO is fairly light on bass, but it's some quality stuff. First off, extension is outstanding for an armature with the IO able to reproduce the opening rumble on Kavinski's “Solli”. While it's often hard to tell thanks to the lack of emphasis, the IO can certainly provide a satisfying low end experience. Juice Aleem's “The Fallen” absolutely relies on it's strong bass line to carry the track and the IO takes it on like a professional. Texture is fantastic too, as evident on Tobacco's work on his joint effort with Aesop Rock, 'Malibu Ken'. The IO picks up all the grunge and distortion Tobacco layers onto everything, and tosses it back at you with aplomb. In addition to having plenty of texture, the IO's low end is pretty quick, as is common with armatures. Each note of the rapid double bass found throughout Havok's album 'Time Is Up' is well defined.

When it comes to sound stage, the IO's intimate presentation results in a fairly “in-the-head” type of listening experience, with effects and notes dancing off into the distance every once in a while. It really shines in it's depth portrayal which keeps instruments and effects well layered and separated, and restricts their ability to interfere and blend in with each other. Imaging is quite good with sounds very accurately transferring across channels. I found the IO to be a nice companion when playing competitive games like Counter Strike or PUBG where accurate imaging helps give you an edge in testy situations.

DSC_0949.JPG IMG_4703.JPG IO.jpg

Select Comparisons (volumes matched using Dayton iMM-6):

EarNiNE EN2J (267.00 USD): The EN2J and it's twin armature setup is much more balanced. Mids and treble are more forward than bass which is quite neutral, but neither steps forward as aggressively as it does on the IO. IO offers better extension in either direction, most noticeable in the bass which rolls off before really offering anything in terms of sub-bass. The EN2J's bass is impressively quick and articulate, but I can see the lack of presence being a turn off for most listeners, especially given the IO isn't particularly bassy itself. Mids on the EN2J are less forward but more balanced and slightly more detailed. They also feature that distinct breathy tone characteristic of EarNiNE's in-house armatures. This unfortunately means it's timbre isn't 100% spot on either. While the EN2J's sound stage is reasonably intimate, it comes across slightly wider but not quite as deep as the IO. Imaging, layering and separation is pretty even across the two with the IO offering slightly improved layering. Between these two, the EN2J does the mid-forward, treble prominent signature a little better. The IO certainly takes the cake in the low end, but I prefer the overall balance and presentation of the EN2J.

In terms of build, the IO is much more impressive. The EN2J isn't poorly built by any means, but it's steel housings lack the attention to detail in terms of fit and finish thanks to prominent moulding lines and plastic nozzles that detract from the premium aesthetic they were going for. The brushed aluminum face plate is also very susceptible to scratches, though it does look good. I quite like EarNiNE's cable. While it doesn't feel as durable as Campfire Audio's, the light, flexible sheath completely stays out of the way. I love it. Comfort on both is excellent, though the IO fits me more naturally and remains less intrusive despite the extra size. I think it comes down to the nozzle design which forces the EN2J deep into my ear canal and pressed up against my outer ear. I also find I have to fiddle with it more to regain a lost seal.

ADV GT3 w/ reference filters (299.00 USD): The single dynamic GT3 also has a skewed signature, this time towards a v-shaped sound. Bass doesn't dig quite as far as the IO's armature but with the IO's lack of sub-bass presence it doesn't feel like it. Mids of the IO are more forward and prominent, upper especially, yet similarly detailed and clear. Timbre is more accurate on the GT3. Treble on both earphones is sharp and crisp with the GT3 sounding tighter and more controlled. The GT3's peak around 6k gets tiring, though I can say the same for the IO's peak further up. The IO has a more intimate presentation with a smaller sound stage, but provides a more impressive job of moving sound between channels. Layering and separation is equally good. I prefer the IO at lower volumes while the GT3's dynamic provides more entertainment at high volumes, though that treble can be unpleasant.

In terms of build both are outstanding with flawless fit and finish, top tier cables, and cool designs. GT3 has a slight advantage in that it brings tuning filters to the party, whereas the IO is more ergonomic. Not only is it heavier, but the GT3 has a very sharp rear end which in some ears will cut into flesh and cause discomfort. I thankfully don't have that problem during regular listening, but on a few occasions I have forgotten about that edge and when going to lay down jabbed my ear when the iem pressed into the pillow.

BGVP DM7 (299.00 USD): The six-armature DM7 has a more balanced signature with tighter, less aggressive treble, but it lacks the extension and upper treble presence making it come across somewhat numb. Mids on the IO are generally more forward and crisp with better clarity and additional detail, though somewhat artificial and thin when compared to the DM7. DM7 has the lead when it comes to timbre. On select tracks, such as Radiohead's “Weird Fishes”, vocals on the DM7 come across more prominent in the mix. Bass on the DM7 doesn't extend as far and sounds heavier, slower, and more mid-bassy. IO has a wider, deeper sound stage and does a better job of portraying various layers to a track, as well as separating individual elements. DM7 sounds more constricted and almost congested in comparison. I prefer the DM7's overall tune but appreciate the IO's technical proficiency.

In terms of build, IO is vastly superior. The DM7 is 3D printed which is in itself just fine, but my DM7 is a bit sloppy around the nozzle and in general feels less durable and looks less premium than the IO. There is also that loose MMCX port issue BGVP is currently dealing with, or has already dealt with if you're reading this well into the future. Speaking of MMCX, both products have very nice cables with the DM7's being thicker and more impressive looking. I think they're equally solid, but I will say Campfire Audio has the better preformed guides. BGVP's are somewhat loose around the cable and when it flexes you can hear ticking as the guide sticks and rubs against the wiring within.

Final Thoughts:

The IO is the kind of product that makes me hate having to put down a score when posting a review to Head-fi. On one hand, I entirely understand the criticism that has been levied at it's unique tune. It's bright, it can be tiring, it can be kinda harsh, and it's not particularly natural sounding. I also found the mid-range inconsistent in it's presentation across a number of vocalists. On an objective basis, it has issues.

However, enjoyment of an earphone is a subjective experience because everyone is unique. A headphone that measures near perfect, assuming the Harman curve is our target for perfection, will be both loved and hated because there is no one tune that everyone universally considers “good”. The IO isn't an earphone for the majority, and that's okay. Those who like it are probably going to like it a lot. It's a fun, vibrant listen with decent technical prowess, great bass that takes you by surprise, and loads of detail and texture to go around. I wish it was a little easier on the ears and that it's midrange and treble peaks were more relaxed, but that's where an EQ comes in, pending you're not opposed to tweaking your purchases.

While the IO's sound signature is tuned for a specific crowd, the rest of the package is undeniably, universally fantastic. The unboxing experience is fun and attractive, and once you get inside you are treated to an extensive accessory kit filled with useful tidbits, like Final E tips, multiple mesh bags to organize and store everything, and a fantastic leather carrying case. Criticism has been levied at this case because it looks like something you'd store make up or coins in. I see where people are coming from with that. However, such cases are ergonomic and designed to be carried and interacted with frequently. This new case is just as spacious inside as Campfire's old cases, but significantly more pocket friendly and easier to get the product into and out of. I think it is a fantastic addition and have no issues with it's inclusion.

I like the IO, warts and all. If a bright, mid-centric earphone sounds like your jam, give it a shot. You'll probably like it. It does that sound fairly well. For everyone else, there are lots of other products out there to cater to your specific preferences

Thanks for reading!

- B9Scrambler

***** ***** ***** ***** *****

Some Test Tunes:

Aesop Rock – The Impossible Kid (Album)
Hail Mary Mallon – Are You Going to Eat That? (Album)
King Crimson – Lark’s Tongues in Aspic (Album)
King Crimson – Starless and Bible Black (Track)
Supertramp – Crime of the Century (Album)
Infected Mushroom – Legend of the Black Shawarma (Album)
Gorillaz – Plastic Beach (Album)
Massive Attack – Mezzanine (Album)
Fleetwood Mac – Rumors (Album)
Run the Jewels – Run the Jewels (Album)
The Prodigy – The Day is My Enemy (Album)
Tobacco – F****d Up Friends (Album)
Felt – Felt 2 (A Tribute to Lisa Bonet) (Album)
Michael Jackson – Thriller (Album)
The Crystal Method – Grace (feat. LeAnn Rimes) (Track)
Jidenna – Long Live the Chief (Track)
Skrillex – Ragga Bomb (Track)
Big Grams – Run for Your Life (Track)
Funkadelic – Maggot Brain (Track)
Aesop Rock – Fishtales (Track)
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Pros: Wide soundstage
Fast speed and transients
Good detail retrieval at this price
Wonderful aesthetics and accessories
FIt is very comfortable
Improved Cable
Cons: Mid tuning is recessed and veiled

The all-new IO is the latest from Campfire Audio, and features a whole new packaging style and build than their previous iterations. The new IO features two balanced armature drivers within each of its garnet red shells. The IO has a sensitivity of 109 dB SPL/mW and 26 ohm impedance at 1KHz, and is being offered at $299, putting it between the Campfire Comet and Campfire Orion, in terms of affordability.

I received this loaner unit as part of The Community Preview program at The HEADPHONE Community, which is hosted by This review was conducted over a couple weeks using various sources (DAPs, desktop amp/dacs, and out of an iPad).

This review was originally published at

The All-New Campfire Package

Campfire Audio products have all featured interesting and unique sound signatures that may or may not appease everyone, including myself, but one thing that is universally praised is their packaging and bundled accessories. They’ve always hit high marks with their presentation, quality and abundant accessories and customer service, and the 2019 refresh takes the high benchmark to another level.

The new packaging is a real treat to open up and look at. CFA stepped up their already top-tier packaging and accessories bundle for this new line of IEMs. I was surprised to see that this came with 3 sets of mesh shell cases. These cases were recently offered to help protect the anodized shells from scratches and dents, and now you’ll have a few extras in case you lose one or two.

The garnet-colored shell is more of a dark red/purple tint than what I thought of in the photos, but they look stunning to me. The gold-plated screws contrast perfectly with the red shells and really make these look striking.

The IO also changed the shallower nozzles from their previous lineup and replaced them with the longer Solaris-style nozzles and this makes this shell much more comfortable for me than the Andromeda/Orion and previous generation Campfire products. I barely feel these on my ears and the sharp edges don’t touch the back of my ears anymore.

The new storage case design is reminiscent of a small coin purse, and looks very nice. It’s made of real leather, and hand-made in Portugal. The outside of the case is soft, but sturdy enough, and the inside is padded with wool-like material. It definitely smells the part of genuine leather.

Finally, the new dark gray colored cable is a treat to use, especially when compared to the previous cables used in Campfire products. The cable is thinner than the ones packaged with the Andromeda and Solaris, which I have with me, but is much more usable. Gone away is the memory wire hooks, and replaced is a pre-formed hook that I very much prefer. The cable is soft and flexible, and does not tangle easily, which is a huge improvement over the previous cables.

IO's Unique Sound

The Campfire IO has an interesting, and unique signature and I think it’ll be unusual to many people. The IO is a relatively flat tuning, but has a different mids-profile than more common sound signatures do, which may put many people off. Besides, that, the IEM has very good technicalities and wide soundstage with plenty of details. But let’s go over some of the things I’ve discovered in more detail during my time with the IO.

The low end of the IO is extremely clean and has a touch of warmth to it. The subbass does dig down, but generally stays even keeled throughout. There’s a lot of good to say about how fast the bass attack is, and how good the layer is in this area. It takes a similar general approach of the Campfire Orion in this regard, but boosts the bass and extends it further down, all the while, improving upon its detail level.

This is not an IEM for bassheads. Its for someone who likes quality over quantity and I think the IO does well here, and generally recommend it for songs that are focused more on bass and treble, as it does both of those quite areas quite well.

The mids are another story though. I find them quite wonky, and it has a lot to do with the sharp peak between 1-2KHz followed by a complete cliff, which enders the upper mids almost absent. This is where I find the IO to have quite a “unique” signature. Because of this, I find that a lot of the presence energy inadequate and lacking.
In terms of listening, I find vocals are recessed and off, and specifically female vocals have a weird haze to it. Cymbals, guitars, and other string instruments also exhibit this behavior. It has a low fidelity sound to it – a veil. Deeper male vocals don’t exhibit the same issues as females, though there still is a weird tinny-haze to them occasionally.

In more detail, for a few songs I listened to which feature prominent female vocals like “Dreams” by Fleetwood Mac, the voice of Stevie Nicks is just off. The bass line sounds good, but the cymbals just lose their sense of splash. Nick’s voice is extremely distant, and not only that, she sounds like she’s off-stage behind the curtains somewhere. It’s like the drummer is playing on stage by himself, and the rest of the band is behind the curtains. It’s unusual to me.

In another track, Norah Jones’ “Seven Days”, the haze is not quite as apparent when listening. Jones’ voice doesn’t suffer quite as severely as Nicks does, but I can hear just the slightest of energy missing. It’s not until I start A-Bing back and forth with other IEMs that I notice the severe lack of mids.

I A-B’d many IEMs with the IOs to get a grasp of how other IEMs stack up and one by one switching between the IO and the other model (e.g. Etymotics ER3SR, BGVP DM7, Moondrop Kanas Pro, Campfire Solaris, Campfire Andromeda, Knowledge Zenith ZS7, to name a few), it was like lifting the curtains and letting the rest of the band be heard again.

Going from one of the “other” models and back to IO was like sucking the energy right out of the room. To me, it felt like a bright sunny day, with glorious spring time flowers and animals walking around, and then all of the sudden, dark clouds rolling in, darkening the scene, and the cute animals hiding in fear of the incoming weather. Maybe this is a little bit of an exaggeration, but for someone who is used to listening to more balanced mids, I find the IO tuning of this area very lacking.

The treble region performs well on the IO, despite the upper mid void. The IO extends further into the treble ladder than the Orion and with more sparkle and air than the Comet. While cymbals and hi-hats have good splashy characteristics, they do sound a tad hazy and muffled, as is the entire sound profile.

To attempt to see if I could adjust the frequency response to further match my preferred sound signature, I tried to elevate the upper mid between 3 and 5KHz up quite a bit to bring presence energy back and for the most part it’s successful. That said, it’s not perfection. The edges of vocals and strings have fringes of hazy artifacts remaining, and this could be a combination of the extreme equalizer gains and the remnants of the unique sound signature the IO presents.

Select Comparisons

Etymotics ER3SE
The Etymotics brand started the In-Ear headphones phenomenon and their diffuse-field tuning has remained consistent and popular over the years. The ER3SE is one of their newer single BA products and makes a great comparison and contrast to the IO. The ER3 and the Etymotics bread and butter ER4SR have similar sound profiles, so this generalization can be attributed to both models.

The IO outpaces the Etymotics in soundstage width and depth, and the dual-BA set up really help the IO extend bass and treble better than the ER3SE. I found the detail resolution of the IO to also outshine the Etymotics, however it’s the mid-range tuning that I find the ER3 outperforming the IO by a significant distance. Much of this is already covered in the main body of the review, so I won’t go over it again. The ER3 is a much more intimate sound, but is very neutral and balanced sounding, albeit maybe lacking a little bit of sub-bass and general bass response. The IO does everything right and better for me, except the mids.

Campfire Andromeda
A lot the initial discussion when IO was announced was whether it would be the “baby Andromeda” or not, much like the Orion was hyped up to be. While I find the IO is closer to the Orion as a “baby Andro” contender, it’s not quite there due to its mid-range issues. The bass is lighter on the IO than on Andromeda, but the treble region is equally as exciting and impressive. The mids, while somewhat tame and laid back on the Andromeda, is much more balanced and even-keeled, and does not sound off to me.

The latest BGVP DM7 IEM is priced similarly at $299 as the IO. The two differ quite a bit after that. The DM7 bass response is slower, but denser, but still well controlled. The IO extends higher and has a much wider soundstage and I’d also give the nod to IO for detail retrieval and general technical ability. Again, the mids is where these differ quite a bit, with the DM7 having a much more mid-forward sound, and the IO having a distant, and unique mid signature.

Moondrop Kanas Pro
The Moondrop Kanas Pro is priced at $179 and one of my favorite IEMs at any price point. The Kanas Pro follows a tuning reminiscent of the Harman IEM Target Curve with slightly less lower-bass elevation. As some may know, the mids of the Harman Curve as a little bit recessed, but I find that the Kanas Pro is still more up front in the mid-range than the IO. The bass elevation is similar on both, but the IO is quicker and has better layering. The Moondrop Kanas Pro detail is similar but may be a tad behind the IO, but the general sound signature is much more coherent across the board. The IO extends treble noticeably better than the Kanas Pro, due to its upper end energy.


Overall, I found the IO to be technically capable and having a lot to like about them, however with one single fatal flaw – the mid-range issues. To me, I enjoy upper midrange to be a little bit more forward, and to provide the energy to what I am listening to. It does not have to be over the top and doesn’t even need to be totally even – see my Solaris review – but the IO just doesn’t cut it. The excessive 1.5KHz peak topped with the absent upper-mids makes this something I personally do not enjoy for about 85% of my music library.

The few genres I did find the IO to work well in are some male-dominated acoustic music, drum and bass music, trip hop, and other genres that focus much more heavily on the upper and lower bounds of the audible spectrum. There’s just too much veil in the mids to make me content with listening to music in a different way than I have my entire life.

That’s a little bit unfortunate because I otherwise love the IO’s package. Great build, color choices, fit, accessories, and presentation, to go along with some really great detail resolution, speed, and a wide soundscape that mark the high points of the IO.

In the end, I was hoping for an improvement in the Orion, which in many ways it did, but it also killed off the best part of the Orion – the mid-range coherency.
Ears are genetically different....perception of sound is different from one human to the next (genetics and enviornmental exposure over time).....the mids comments around this IEM is way off for me PERSONALLY(my ears hear it this way but would not try to influence you either way) this because the highs and lows are more forward for a BA and it is confusing to the ear? curious indeed
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Pros: - The design and fit
- Natural, pleasant, easy-going sound
- Great soundstage and spaciousness
- Great accessories and cable
Cons: - Can sound somewhat too distant, lacking intimacy and intensity
I only had about half an hour with the IO at the Munich High End a few days back, so take this review with a grain of salt.

I am currently using the Andromeda S as my daily driver, and absolutely in love with its sound signature, intensity and neutrality/naturality.

Now, the IO is considerably lighter and as such, somewhat more comfortable as well. It instantly found itself at home in my ears (i didn't even have to change the tips or play with those, just pop and in they went). Their design is also absolutely gorgeous, in a dark red with gold screws, they would fit right into an Iron Man movie. Also they make a fine tribute to good old Tony.

The case that it comes with is absolutely lovely, the cable fits well with the color scheme of the IO and performed adequately when I tested it with my Andromeda S.

Now, onto the sound. My impressions are somewhat limited as I didn't have too much time to spend with them, but I will make sure to go to my local dealer and grab a pair for a proper listen.

I listened to a few tracks and they instantly struck me as a lite version of the Andromeda (also confirmed by the guys at Alo Audio). The instruments and vocals sounded somewhat less intimate than the Andromeda, and certainly more distant. The soundstage was quite impressive for a twin BA design, and there was a certain airy feeling. They certainly punch far above their weight class, easily outperforming the Polaris (which I found to have the same weakness as the IO but the bass was just far too intense and invasive) and the Noble Audio Sage (which can sound somewhat too dense, lacking a more spaced out presentation). On the other hand, the Sage performs quite a bit better in the treble region but lacks in the lows.

I really enjoyed the lows of the IO, as I generally like a tight, accurate and controlled bass that doesn't spill over in the lower mids, which the IO did absolutely great in.

All in all I think the IO can make for one amazing daily driver, something to be listened to at work for example, where the intensity of the Andromeda can be plain distracting and even overwhelming at times. They present a fun, natural sound that very few competitors in that price range can boast.

Certainly would recommend :)