Introduction- What is the Campfire Audio Io?
The Campfire Audio Io is an in ear monitor that is one of the more affordable members of the Campfire Audio range. This oddly named company has been in business since 2015, designing and building its products in the city of Portland Oregon. Their range has grown to encompass a wide selection of models that now extend up towards the £2,000 price point and whilst that might have seemed like a lot of money not too long ago, in the current world of earphones, that’s not even near the top of the tree.
The nature of the IEM market has changed of late though. For people using external DAC based solutions for their portable audio, these multi driver flagships are a logical partner to some of the more ornate digital front ends out there. The Io arguably has a rather tougher job because £300 is no longer the preserve of the wired earphone. This price is a key area for smartphone customers looking to boost their listening but retain the phone as the source device. With the 3.5mm headphone socket in full retreat across the sector, the Io has its work cut out.
There’s also no shortage of competition from brands that might be better known in the UK at least. Still, it seems that Campfire Audio has managed to develop a very loyal following in the time they’ve been around and the fact that they are represented in the UK by KS Distribution (the distribution side of HiFi Headphones) who have also brought brands like Final to our attention in the past too suggests that this is a company to keep an eye on. Is the Io good enough to make you want to keep the cables?
Design and Specification
The Io is a twin driver earphone. Each side makes use of a pair of balanced armatures, supported by a basic crossover network. These armatures are not identical and their implementation might be better thought of as like the woofer/tweeter relationship of a two way speaker. There is a larger armature for the bass frequency and a smaller, lighter unit for reproduction of the high frequencies. The crossover between the two drivers is unspecified but one line of the specifications should be enough to raise an eyebrow. The upper frequency response of the Io is a fairly conventional 22kHz but the lower end response is quoted at a very healthy 5Hz which, for an armature design, is very impressive.
Campfire Audio says that some of this is down to the enclosure that the armatures are placed in. This is called a Tuned Acoustic Expansion Chamber (TEAC) and it reflects that the critical part of earphone designs, particularly ones using armatures is that the space they operate in is arguably more important than the drivers themselves. Think of it like a Formula One car- the engines vary to an extent but performance is governed more by getting the power down and moving the air around. Campfire Audio says that the Io went through more prototyping stages than any other model in the range in the pursuit of getting the best from those two drivers.
The enclosure itself is made from sections of machined aluminium which is in contrast to many rival designs at similar sorts of prices that are frequently using moulded housings. There are three sections in total. Two form the body itself and are secured by three 24ct gold plated screws that are visible on the outside face of the Io. There is then a separate tube section that is (presumably) secured to the inside of the inner aluminium section. This body is fairly large as earphones go; larger than rivals that mount more drivers or dynamic types (which are larger than armatures) and this means that it would also count as a fairly large device to have near an ear canal. Campfire Audio has recognised this though and ensured that the tube section of the Io is relatively long and keeps the housing proud of the ear.
This means that while the housing itself is roughly equivalent in location to the pinna of the ear, the manner in which it comes into contact with the ear is well controlled and more comfortable than you might give credit for a straight edged aluminium object being. This is helped by Campfire Audio supplying a genuinely excellent spread of domes with the Io. There are Comply type fittings as well as two different shapes of silicone domes. My general aversion to Comply is as keenly developed as before so I’ve gone with the wide but shallow silicone dome for listening here.
This is just a part of a very well-considered clutch of accessories. The many domes come with elasticated bags to store them and there is a leather carry case that manages to judge the size well, being able to hold the earphones without an issue but still being about the right size to go in a pocket. I’m not completely sure that the key to audio greatness is a lapel pin but you get one of those too.
Necessary or not, the experience of using the Io is one that gives you a sense of quality. Everything about these earphones feels considered and well made. What I think is particularly noteworthy is that despite this being from a small company, nothing feels like it has been thrown together or has that ‘made in a shed’ vibe that can bedevil some products. The paint finish is entirely uniform and of a high quality, shutlines are tight and the overall build is entirely competitive with anything I’ve seen at the price.
There is of course the cable to consider too. This loops around the top of the ear and ensures a good, solid, jogging friendly fit (caveat; no jogging took place but I did thump up and down the stairs a few times with them in). It is detachable, with MMCX connectors at the headphone end, offering a degree of sacrificial protection too. Ultimately, it is still a physical cable with a 3.5mm connector and this means that for many smartphones, it will need an adapter or external DAC to function. To be entirely clear, there is no question that the Campfire Audio can’t outperform a Bluetooth equivalent but the absence of wireless solution for it does mean that many would-be customers are likely to look at rivals that do have this option.
Everything about these earphones feels considered and well made
How was the Io tested?
The Io has largely been used with a Chord Electronics Mojo and Poly running as a Roon endpoint from a Roon Nucleus. Some additional testing has been via Essential PH-1 phone using both the supplied USB to 3.5mm dongle and the Audioquest Dragonfly Cobalt. Some additional testing has also taken place using the Audiolab M-DAC Nano too. Material used has included FLAC, AIFF, DSD, Tidal, Qobuz, a small amount of on demand video and web work.
The Io has one trick up its sleeve that has huge potential benefits for people making use of USB adapters to power it. Almost all armature earphones are sensitive; it’s a fundamental benefit of the design. Even so, the Io is incredibly easy to drive. The Chord Mojo uses a volume control that changes colour as you increase the volume, running from red through to white. The Campfire Audio needs so little oomph to drive that this system doesn’t actually work and the Mojo spends its life with weird half illuminated buttons in the ‘sub red’ zone. By the time that the red indicators are lit correctly, the Io is running seriously loud. This means that it really doesn’t matter how anaemic your headphone output or dongle is, the Io can almost certainly work with it.
Thankfully, this useful skill represents the beginning rather than the limit of the Campfire Audio’s talents. Listening to the spellbinding modern classical of Hiddensee by Ceeys, the Io manages to do things that earphones can often struggle with. There is an effortless space and three dimensionality to how it makes music that really benefits these simple, brooding pieces. Put simply, it doesn’t feel as if someone has wedged a piano into your ear canal. It escapes this confinement and there is a genuine feeling of music happening ahead of you - always a neat trick with any earphone.
The tonality is also top notch. Give the Io about ten hours; it can feel a little hard edged before that point, and it delivers the basics pretty much perfectly. In Human Hands, the opening track of Bill Fay’s utterly lovely Countless Branches, is absolutely wonderful via the Io. This is a very human performance, Fay is not a virtuoso pianist and his works are irregular and slightly rough edged. The Io takes all the nuance and detail and makes it a real and tangible thing. At the same time, this isn’t the sort of performance that is truly warts and all. The Io is able to take the deliberately edgy presentation of Thom Yorke’s Not the News and ensure that it stays listenable.
Move from the Chord to the Dragonfly Cobalt and the results are arguably even better. The smoother, slightly warmer presentation of the Audioquest partners with the invigoratingly fast Io to make for a performance that is greater than the sum of its parts. It also gives a partial answer to the circumstances of how you might use this wired design in a convincing way with a modern smartphone. It’s certainly more convincing than relying on a dongle. The Io serves to remind anyone who’d forgotten that sensitive devices are not necessarily forgiving ones. It has a noticeable edge to the presentation when used with the PH-1 dongle and there is enough of a sign that it is present with the (reasonably good) headphone output of my Lenovo ThinkPad too.
Happily, one convenience option that works well is the Audiolab M-Dac Nano. To be clear, the Audiolab can’t match the wired connection performance of the Audioquest Dragonfly but it is good enough to ensure that the Io can deliver much of the natural talent it displays. There are valid arguments as to whether it makes more sense to simply choose a Bluetooth device from the outset but if you are switching between wired and wireless use, the Audiolab and Campfire Audio working together makes for a very strong partnership.
One final welcome note about performance is that it applies to an earphone that is very comfortable to wear for extended periods. There are clearly some people in the Campfire Audio team who have really put some time and effort into the process of designing this shape (which is shared with more expensive models too) because it genuinely works well for extended periods. In the process of some considerable ‘self-isolation’ listens, I racked up runs of four to five hours without discomfort and there aren’t many rivals that can stick with that.
There are clearly some people in the Campfire Audio team who have really put some time and effort into the process of designing this shape
- Open and expansive sound
- Well made and well specified
- Won't flatter poor sources
- No wireless option
Campfire Audio Io In Ear Earphone Review
The simple truth of the matter is that in 2020, a purely wired earphone is not going to work for everyone. If you want to move across a busy town or city without an umbilical linking your head to your pocket (and while that isn’t happening very much at the time of writing, it will soon enough for many of us), the Io is reliant on extra equipment to do what some rivals can do directly.
Judged on its own merits though, the Io is a truly great earphone for the price. This is a spacious, detailed and effortlessly musical earphone that is supplied with great accessories and is a pleasure to wear and use. Some elements of the Io are a little old school but if you can work with that, very little at the price can get anywhere near it and for those reasons, it comes Highly Recommended.
Our Review Ethos
To comment on what you've read here, click the Discussion tab and post a reply.