Campfire Audio IO

General Information



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

Remarkable. Refined.

IO is a special earphone. It is a remarkably expressive earphone. It delivers a refined sound that is also exciting.

Many more iterations and unique prototypes were made of Io than any other earphone in Campfire Audio’s line up to date. It was a journey to fine tune the sound and get it right. The result is an earphone that we can proudly stand next our best-known models. We feel confident you will enjoy the result of this effort.

Based on our classic Campfire Audio profile, Io features a ‘Garnet’ Red Anodized Finish with 24K Gold Plated Screws. Stainless Steel Spout and Machined Aluminum Body are paired with a custom beryllium / copper insulated round MMCX connector.

Each earphone is assembled by hand in our workshop in Portland, Oregon by our team of highly skilled craftspeople.

Insides that Count
Driver count has never been as especially important to our designs as the proper selection and implementation of particular drivers. When using more than a single driver, it is as much about the synergy between drivers as it is about any one particular driver.

Staying true to the Campfire Audio design philosophy “Less is More” and using fewer, higher quality components is ideal to achieve a more a musical presentation.

Using an oversized woofer BA as a foundation and then pairing that with a small tweeter, IO came together. Our Tuned Acoustic Expansion Chamber (T.A.E.C.™) provides that natural and open top-end extension people have come to expect from Campfire Audio earphones.

New Cable + New Case
Building from our Silver Plated Copper Litz wire conductors and our popular tangle-resistant twisted cable weave, we’ve added a new stylish Smoky jacket to compliment the unique finish of our new line of earphones. A new light-weight molded ear-hook design replaces the memory wire. The result is a light weight cable that is a pleasure to use everyday.

Our exciting new premium ‘Bordeaux’ leather protective zipper case is an update to our standard leather earphone case. Luxurious leather surrounds a substantial and protective rubber barrier that ensures that your earphones will remain safe while in transit. The interior is a dense faux wool lining that preserves the anodized finish of your earphones. Each case is made in Portugal by a small team of skilled crafts people that share our commitment to quality.

Designed and Assembled in Portland, Oregon USA

Each unit is assembled by hand in our workshop by our small team of highly skilled craftspeople. From driver to body each component part is carefully examined and tested. After each unit is built, it is placed into a pairing pool, where it finds its ideal sonic match.

Premium Custom Connectors
Our custom Beryllium Copper MMCX eliminates the traditional shortcomings of the connection and harnesses all of its benefits. Beryllium Copper provides a robust mating mechanism; one that is typcially made from soft brass. This selection of a harder material extends the life of the component and the earphone.

2 year Warranty
Each unit we make is backed by our 2-Year Limited Product Warranty. Rest assured when you purchased a Campfire Audio earphone, it will be a great ownership experience. Learn more about product warranty and product repair policy here.
Included Accessories

Premium Campfire Audio Leather Earphone Case. Made in Portugal.

Campfire Audio Smoky Jacket Litz Cable – Silver Plated Copper Conductors with Berylium Copper MMCX and 3.5mm Stereo Plug. Features formed ear-hook without memory wire.

Final Audio Tips (xs/s/m/l/xl) – Campfire Audio Marshmallow Tips (s/m/l) – Silicon Earphone Tips (s/m/l) – Campfire Audio Lapel Pin – Cleaning Tool

Packaging Details
Authentic Campfire Audio Earphone Packaging

USA Made “French Paper Company” Paper

Printed Locally in Portland, Oregon USA

Authentic Warranty Number Sticker – Matches Interior Warranty Card


Latest 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


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