Fit and Comfort

Seen above is the right channel of the Astell&Kern x Campfire Audio PATHFINDER placed into an artificial ear mold with the included softer flange size M silicone ear tip installed. I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. Size M silicone tips are my go-to for testing, since foam tips are not included by some brands, but note that Campfire Audio has its foam tips pre-installed on the PATHFINDER so you may want to try it out first. The PATHFINDER is a medium-sized set that fits in the ears comfortably owing to the taller profile, although it's not necessarily an ergonomic shape in itself. Helping matters further is the use of a slim nozzle that also is longer than average to provide for a secure and comfortable seal in my ears, and those with smaller ear canals need not worry either. The shells weigh ~7.5 g each owing to the all-metal construction and that ends up feeling solid in the ears as opposed to being physically fatiguing if heavier or giving you a sense of being loose if lighter. The MMCX connectors are naturally angled upward to make the ear hooks in the cable also easily go over and around the back of the ear for further support as needed, with the freely rotating connection aiding this. I don't have any complaints on the fit and comfort of the IEMs themselves but would have still appreciated a cable that is easier to handle as pointed out on the previous page.

Audio Performance

Audio Hardware

The PATHFINDER employs a hybrid driver configuration that also makes use of Campfire Audio's recent successful R&D work with 3D printed acoustic chambers. Note how the red-colored chamber allows for the radial venting we saw earlier and this allows for the sideways placement of two new 10 mm custom dynamic drivers to handle the lower frequencies. Each driver uses a polyurathane and liquid crystal polymer composite diaphragm and the duo then give way to a new dual chamber, dual diaphragm balanced armature driver from Knowles for the midrange. The higher frequencies are catered to by custom dual balanced armature drivers incorporating Campfire Audio's T.A.E.C. (Tuned Acoustic Expansion Chamber) technology that "expresses high frequencies without fatigue or sibilance." These all come together to make for a set of IEMs that is extremely efficient and, in typical Campfire Audio style, has an ultra-low specification of just 6.2 Ω rated impedance and a sensitivity of 94 dB @1 Hz 13.49 Vrms which isn't trivial to compare against pretty much everyone else who reports values in dB/mW—why can't you do this too, Campfire Audio? The bottom line is that, if anything, you need to be concerned more about a dark background with your source rather than worrying about whether it has enough power to drive the PATHFINDER. I ended up pairing it with the aforementioned Qudelix-5K as well as the Questyle M15 for my listening needs. Between the two, I was also able to test all three provided cables to confirm there is no discernible difference in the audio signature from them outside of the balanced connections making for a louder output.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature with a slightly elevated bass, smooth treble range, detailed mids, and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the Questyle M15 portable DAC/amp. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry instead of just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the PATHFINDER. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are practically identical across the entire useful 20 Hz to 20 kHz range! The measured discrepancy at ~5 kHz is a measurement artifact that comes out of matching the coupler resonance to 8 kHz, and in practice a proper deep fit had the resonance hit closer to 9 kHz on my coupler, at which point the two channels were spot on, meaning in your ears they will be identical too. This is a randomly picked retail unit sent from the Astell&Kern, so I am very happy with what I saw and heard here. Measurements taken after 75 hours of testing, which included these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The response with the anthropomorphic pinna in place matched the ideal scenario in the coupler extremely well too and this is an indicator of how good the seal was when installed in the artificial ear.


Here is the average frequency response for both channels of the Astell&Kern x Campfire Audio PATHFINDER plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. Indeed, with a slew of Harman-like and warm-neutral tonalities recently thanks to audio brands aiming to appease reviewers and their followings, I was somewhat hoping to see good executions of other tuning styles too. No matter where you stand on Campfire Audio and Astell&Kern products, there's no denying they do try out new things and the PATHFINDER continues that trend without going overboard and alienating people.

Indeed, at first glance you can see the PATHFINDER adopt a warm and forward tuning before the higher frequencies get a bit wonky. But here's the kicker—I always listen to IEMs and headphones for a good while before measuring them so as to not have any pre-conceived notions driven by the frequency response.—the PATHFINDER sounds better in the ears than it measures! What may look like boomy bass and a darker treble ends up being more warm on the lower side and with decent extension on the higher frequency end. There's ~9 dB bass boost from the lowest point in the mids that happens to be at 1 kHz, and this makes for a less-boomy but also slightly less impactful bass than what you might think. The dual drivers are punchy in the mid-bass proper and have a good amount of detail to them although it's not a set I'd recommend for fans of electronic house. The cross-over to the balanced armature drivers for the mids is well executed with male vocals being fairly pronounced and instruments still getting their due.

What can be an issue is leading notes for female vocals coming off hollow or shouty depending on the artist—sometimes both simultaneously in an impressive display of poor performance—whereas trailing ends feel slightly neglected too with the 4.5 kHz presence only helping so much. The set does take to EQ well although it is quite hard to get the upper mids presence out exactly as I wanted it owing to the recessed 2-4 kHz region on either side of peaks. Imaging takes a slight hit to an extent too owing to the uneven tonality but not enough to be a dealbreaker in itself. Instrument separation is excellent and I was also pleasantly surprised by the soundstage here which comes off faithful in reproducing the recordings—never too cramped or artificially bloated. The higher frequencies are mostly featured in the mid-treble and I did have a resonance at ~9 kHz in my ears which can affect harmonics and string instruments. I still quite liked the set for acoustic jazz and piano music though as I did also for rock and country music. The PATHFINDER isn't a universal pleaser and ends up more fitting a few genres that it does work with quite well to where I would like to see both brands take this as a base and then build further upon it for the upper mids and lower treble in particular.

Comparisons

The Astell&Kern x Campfire Audio PATHFINDER is among the pricier IEMs I have featured to date and here is where you start to see IEMs that try to do their own thing to appeal to customers who already have a better idea of what they want. People generally still like bass though, and interestingly we see the three other comparisons chosen here go a similar approach in this regard, be it the Custom Art FIBAE 7 Unlimited with seven BA drivers, the Lime Ears Pneuma with its hybrid 1 DD + 4 BA driver configuration, as well as the ThieAudio V16 Divinity with a whopping 16 BA drivers per side. The PATHFINDER ends up being more expensive than all of these, albeit only just compared to the Pneuma to where I would certainly go the PATHFINDER route given it handles various music genres better than the Pneuma tries to, while also being arguably better built and objectively more comfortable to listen to. I do not have the FIBAE 7U in UIEM form so I can't tell you about the build and comfort aspect but I feel it is a better take on a similar idea the PATHFINDER was going for to where I'd personally pick it over the PATHFINDER for most things except perhaps mid-bass reproduction that the PATHFINDER does excel at. The V16 Divinity is also larger than the PATHFINDER and can be a literal pain in the ears for some but this is the strongest competition of the various offerings I've tested in the price range with its fun-yet-articulate sound. There are of course a few other wonky IEMs such as the Effect Audio Axiom which is innovative but the base package at least doesn't even merit being in the consideration price-wise. Then there are others such as the Symphonium Helios which—if you can manage the fit—would be excellent value for money. Suffice to say that the PATHFINDER isn't at the top of my personal list when it comes to what you get for the asking price, but I am sure it's exactly what a few others are looking for.