Campfire Audio IO In-Ear Monitor Headphones - Official Thread

Great work as always @antdroid.

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Hey all. Still spending some more time with these to make my comments more legit and insightful.
Bare with me. The I0’s tuning is quite unique to me. It is hard to form exacting comments and opinions at this point of only 2 weeks of listening just on my way to work and back.

Talk soon. Hope all is well and happy Friday! :smiley:


Check out @antdroid’s full review of the IO, just posted on!


Great review @antdroid! We still need to meet up soon… probably next week! I should have more bandwidth for a lunch meeting or coffee meeting.

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Thanks! The IO is a very unique tuning, and I’ll give CFA credit for trying something new here. If the mids were tuned more like Orion, this would be a slam dunk top rated IEM for me.

Yea, this week has flown by and what not. I may be a bit busy next week but I can probably find time to meet up. Do you want to check out the IO too?


I think I’m good on IEMs :wink: they really just aren’t my thing… I wouldn’t want to waste anyones time trying to review them lol.

If not next week I am free the beginning of the following week… but I would have to check my schedule…

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Hi guys! I’m new here, just purchased a pair of Solaris myself today but am just having fun reading impressions/reviews in the meantime. I think there’s a small typo in your review @antdroid when referring to the andromeda having a dynamic driver for the bass - I think you possibly meant Solaris? Cheers.


Ah! good catch. Yea I mixed my IEM specs up. Maybe @Torq can help and edit that line out. I do find the IO to feel tighter/quicker than both Andromeda and Solaris in the bass kick department.

Also - Welcome to the forum and thanks for the immediate help :smiley:


Done! :wink:


It’s like it never happened.


Interesting, I can appreciate how each IEM has it’s own signature and it’s good at something in itself respectively (Solaris is holographic, Andromeda has the sparke, Atlas has the bass, etc.), and not a problem :slight_smile: I noticed it so I figured why not point it out, thank you for the good review/read.


Yea, I’ve been juggling a dozen review IEMs right now and getting my wires crossed. I love the Solaris. I also recently purchased them as well.

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Hello and welcome @Tristan_Wolfe. The more the merrier. :grin:. Hope you’re enjoying your Solaris. I’m a big Campfire fan myself.


Thank you for the warm welcome ! :slight_smile: I haven’t actually received them yet but I should have them by Tuesday so I can’t wait to hear them then. I have experience with Noble K10’s, Senn ie800’s, and Andromeda’s for higher end IEM’s. Andromeda was definitely my favourite so I’m curious to see how my ears like Solaris compared to Andromeda. I’ll either end up keeping the Solaris, or repurchasing a pair of good old Andromeda’s. What makes you a CA fan?

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I have the Andromedas and am a big fan. I love the sparkle that they have. I love the treble too. The whole sound signature is spot on for me and my tastes. They are just such a great set of iems. I haven’t tried any other campfire stuff. I would have liked to get a pair of Solaris myself but I went in another direction instead.

I like the whole experience you get with Campfire and their customer service has been great.


Thanks to the community preview program I was able to evaluate the Campfire Audio Io and the Polaris V2. I’m catching up on posting some of my impressions after a crazy few weeks at work.

My general take is this: These are better than I expected.

I suppose I made the mistake of looking at the frequency response measurements for the Io before listening to them. This IEM has generated its fair share of criticism with its extreme upper midrange cut. But I think it’s also important to consider the context of where the Io fits price-wise. I know that for many people $299 is the most they’d ever consider spending on an IEM, but within this hobby I’d consider the Io closer to an entry level product - especially when considering the rest of the Campfire Audio lineup. With that said, I always find that with IEMs at this price point, they struggle to do two things right, namely treble response and bass extension. They can sound good, but often at the cost of one or both of those aspects.

The Io somehow manages to absolutely nail both of those. Usually I find that the treble rises too early, causing the splash to sound slightly compressed and occasionally the tonal focus can even be a bit harsh as well. And then almost every single IEM I’ve tried under the Andromeda has substantial treble roll-off above 10khz. Not only does the Io rise at the perfect spot for treble splash without causing sibilance, harshness, or compressed sound, it doesn’t roll off until beyond 12khz. This causes it to have possibly the best treble extension I’ve ever heard at this price point, and I can think of a number of IEMs three times the price that the Io outperforms in the treble. It also has possibly the best soundstage I’ve ever heard at this price point as well. Something about Campfire’s T.E.A.C system is doing good things here.

Similarly, the bass is well-controlled, extends deep, and doesn’t bleed into the midrange the way some of the more ‘V’ shaped IEMs do. While this is less ideal for commute purposes with ambient low-frequency drone sounds often overpowering bass presence, in more optimal environments this is exceptional. On balance this is a fairly neutral IEM with a slight upward tilt and treble focus.

Now to the bad stuff. The upper midrange cut between 2-3khz is probably where the dual BA drivers cross over, leaving a substantial piece of information significantly subdued. This causes female vocals to sound a bit dry and hollow. But 2-3khz is also right where the ear canal and ear drum resonance amplification occurs (at least according to this), and so how bothersome this cut is will depend on the amount of canal + drum amplification. Or in other words, this will depend on the listener. Without getting too much into the whole objective/subjective thing, there’s room for differences in appreciation that are grounded in physiological differences between people, and we need to remember that ideal targets are based on averages, not specific ears. Without question, the 2-3khz dip is a bad thing, but I’m not finding it nearly as bad as I expected, and that’s likely to do with A) how much my brain expects the ear canal + drum amplification and B) how much my ear canal + drum specifically amplifies 2-3khz (for all headphones/IEMs).

In a perfect world we’d be able to measure all the different parts of our ears to identify where the amplification occurs and to what degree, and then EQ things accordingly, but unfortunately we’ll have to settle on averages for now and do it by ear. The bottom line for the Io is that while it has one major flaw, it does many other things beyond my expectations for this price point. And for me, those outweigh the primary issue. I’d even go as far as to say I prefer the Campfire Io over the Polaris V2, and many other more expensive IEMs. The Io reminds me most of the Campfire Jupiter, which had a similar upper midrange cut. But remember, that’s also a much more expensive IEM. So in a sense, this builds out Campfire Audio’s more neutral and less ‘V’ shaped lineup - something they’ve needed to do for some time.

You can check out my video review here


Nice review and video! You’re getting pretty good at this stuff.




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 risky for that midrange peak alone.


Nice write up. It’s a shame that Campfire seem to have misfires a little on this one. It’s a nice looking iem and I will reserve judgement myself until I hear it myself, if I ever do. It’s not one I would buy myself. Again thanks for sharing your thoughts on this.


It is a shame. Anecdotally, it seems it’s their worst product. I’d guess so myself, because I feel like if something of theirs was worse, we’d know about it.

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