Campfire Audio remains one of the most unpredictable IEM brands out there. While many companies play it safe, pumping out variations of the same shell design and sticking close to well-established tuning targets, Campfire marches to the beat of its own drum. Whether it’s materials, shape, color, or tuning, you never quite know what you’re going to get—and that’s half the fun. At $999, Alien Brain’s retro sci-fi aesthetics certainly aren’t playing it sage, but does the sound match the look?
Build and Design
Right out of the box, Alien Brain delivers a premium experience. Included are two Time Stream cables (3.5mm and 4.4mm), a high-quality carrying case, a USB-C dongle DAC, and a generous selection of eartips. They even throw in a pin, microfiber cloth, and cleaning tool – just the sort of experience we’ve come to expect from Campfire.
The IEMs themselves feature a sleek black stainless steel housing accented with blue aluminum and topped with an iridescent translucent dome that gives a peek into the internals, giving the IEMs their namesake “alien brain” looks. The shell is compact and ergonomic, offering a comfortable fit that won’t be too snug. Internally, you’ll find a single dynamic driver handling the lows and four balanced armatures taking care of mids and highs, all tied together with a 3-way crossover.
Sound
Campfire’s been known for bold, often unconventional tuning decisions, but Alien Brain takes a more grounded approach. In fact, it’s probably the most "by the book" tuning we’ve seen from them so far.
Alien Brain delivers deep sub-bass extension with clean, tight midbass. It’s punchy without being overbearing, offering excellent texture and a satisfying low-end rumble that shines with the right tracks.
There’s a subtle scoop in the midrange that adds a sense of space on some tracks but can make certain instruments sound a touch hollow. Vocals are generally clear and well-balanced, though some wispy female vocals can lean into sibilance.
The top end is crisp, airy, and slightly relaxed. There's decent extension and a good sense of breath, but it doesn’t aim for aggressive sparkle. If you’re treble-sensitive, this could be a sweet spot.
Soundstage and imaging is where Alien Brain really excels. The stage is impressively wide and deep—easily one of the most expansive in its price range. Imaging can be a little diffuse, but positioning and separation are still strong.
Alien Brain is very sensitive to your source, and definitely prone to pickup background noise and interference. I wouldn't recommend it with a tube amp, and it had a slight hiss with any number of more powerful sources, however, the DAPs and non-tube dongle DACs that I tested from FiiO, iBasso, and Astell&Kern all sounded great with no issues.
On Florence + The Machine’s “Dog Days Are Over,” the opening chords echo warmly, and the vocals come through with rich intimacy. As the track builds, each element is layered cleanly without congestion. Instruments stay grounded while ambient reverb fills the space, giving a great sense of depth.
With Daft Punk’s “Lose Yourself to Dance,” the low-end feels textured and impactful. The kick hits with authority, while the hi-hats and claps snap into place. Vocals float just ahead of the mix, and the panning robotic effects show off Alien Brain’s spatial capabilities with style.
On a solo piano piece, like Idil Biret’s performance of Chopin, Alien Brain maintains realism with a hint of smoothness. The dynamics are there – both micro and macro –but the highs are a bit rounded off. Those mezzo-forte chord tops have a little bit of bite, but are softened just enough to be easy on the ears.
Comparison: Thieaudio Monarch MK3
The current king of the $1000 and under price range is the Thieaudio Monarch MK3. Just like its predecessor Monarch MK2, MK3 was a huge hit, beloved by both critics and audiophiles. Its solid tuning and technical performance have made it the easy, “default” choice when buying an IEM in the $1000 range, but considering its similar qualities, should Alien Brain be part of the same conversation?
Alien Brain gets the clear win in build, design, and comfort. Its build feels more premium, and the smaller shell offers a more universally comfortable fit. Monarch MK3, while solid, is starting to feel outclassed by newer offerings – even those from lower price tiers.
The difference in sound comes down more to taste. Both aim near the Harman In-Ear Target but deviate in different directions. Alien Brain boosts the mids slightly and tones down the upper mids and treble. Monarch MK3 has more upper mids and adds a little extra treble energy. If you like brighter, more energetic sound, Monarch MK3 might be more your thing. If you prefer a smoother, less fatiguing listen, Alien Brain could be the better pick. That said, Alien Brain does have a bit of a peak around 10kHz, which some may find fatiguing.
The Bottom Line
Alien Brain may not hit you with an immediate wow factor, but it’s a consistent performer with excellent tuning, a killer design, and top-tier accessories. Campfire Audio has fused its signature craftsmanship with a crowd-pleaseing sound, creating an IEM that easily deserves a top spot in the $1000 tier.
