Flathead Audio Cielo Review: A Gateway to IEMs That Might Lead to an Earbud Addiction Instead

For those in the IEM or Chi Fi space, Flathead Audio might not be a name you immediately recognise. Despite being relatively new, the brand has already built its reputation in the flathead earbud community, with favourites like the FH-STUDIO, FH-PEAR and the inaugural FH-01.

For those that follow the niche earbud scene, that name would undoubtedly ring a bell. Even so, this new release is likely your first encounter with them in the in-ear monitor world.

What Is It?

The Flathead Audio Cielo is the brand’s first attempt at an in-ear monitor and they have chosen to go with a bullet-style form factor. Unlike the typical ergonomic resin shells that rest along the concha, bullet-style IEMs use a cylindrical housing that sits within the ear canal. It can be seen as more of an old school approach and one that feels closer in spirit to earbuds, just with better isolation.

The shell of the Cielo is made from aluminum alloy and isn’t a straight bullet shape but features a bit of a curvature to better fit into the ear canal and guide sound to the eardrum. There’s also textured knurling along the outer edge of the shell that provides a better grip when putting on or taking off the earphones, while also adding a bit of character. The Flathead Audio logo and Cielo branding are also present on the shell.

With flathead earbuds as its roots, the Cielo positions itself as an entry level IEM aimed squarely at flathead users who are curious about making the jump. Flathead Audio seems serious about that transition because every purchase of the Cielo also includes the FH-01 flatheads in the box. Those normally retail for around 30USD on their own, so this isn’t just a token freebie, especially since the Cielo have an introductory price of 40USD.

The goodies don’t stop there. In the box you get a round hard shell carrying case, a pure OFC, MMCX cable that can be terminated in either 3.5 mm or 4.4 mm (the version we went with), a cable clip, three pairs of wide bore silicone tips, three pairs of hybrid (silicone and foam) tips, a logo keyring and a silicone sticker with the Cielo plane motif that also doubles as a keyring. This is a surprisingly generous set of inclusions for something positioned at the entry level and is something that should be more prevalent in the hobby.

Flathead Audio’s own AK 2110 Bluetooth adapter is also designed to pair seamlessly with the Cielo, forming part of a modular ecosystem within the brand.

The name Cielo actually comes from the Spanish word for ‘sky’. The idea here is simple: You would ideally listen to flatheads everywhere if you could, but when you need isolation, like on a plane in the sky, you’d reach for an IEM. The Cielo is meant to be that on-the-go companion you can rely on.

The bullet shells are metal but still lightweight and compact, easy to insert and comfortable for longer sessions. Isolation is decent for a bullet style IEM, though the fit will depend heavily on your ear anatomy and tip selection, it also plays quite a major role in the sound.

How Does It Sound?

Since the Cielo is meant to act as an entry point for flathead enthusiasts, I expected some tuning similarities to the bundled FH-01. While there is a hint of that DNA, the Cielo ultimately goes in a different direction.

The overall tuning leans neutral bright with a noticeable emphasis in the upper midrange. The presentation is quite forward and intimate. Soundstage width is narrower than what you would typically get from flathead earbuds, which may surprise those coming from that style of earphone.

Starting with the bass, the Cielo is light-footed, to say the least. Sub-bass presence is minimal and there is not much rumble to speak of. Mid-bass impact is also very restrained, with limited extension and decay. Notes do not carry much weight and the bass feels a little slow and soft edged rather than tight and punchy. Swapping to ear tips that emphasise bass will add more oomph but that may dampen the mids and highs, depending on the tips used.

The midrange is clearly the focus. Everything sits front and centre, creating an in-your-face presentation. That being said, male vocals lack body and fullness, sounding somewhat lean. Female vocals cut through more clearly but come across thin in note weight and at times slightly hollow. On certain tracks the upper mid emphasis can border on shouty, especially at higher listening volumes. That being said, the overall presentation and timbre of the mids are relatively natural, albeit a touch too intimate.

Treble is bright with a bit of heat in the lower treble region, though it does not quite cross into sibilance. The upper treble rolls off earlier than expected, which limits sparkle and extension. Cymbals and snares lack that crisp bite and shimmer. There is a decent sense of air, but overall detail retrieval is average at best. The presentation can come across slightly grainy and, dare I say, a touch ‘lo-fi’ on more complex songs. On busier tracks, the narrow stage and forward mids can make things feel congested, more so on higher volumes.

One thing that cannot be overstated is how tip dependent the Cielo is. The stock wide bore silicone tips are comfortable but push the brightness further than I would like. The pink foam and silicone hybrid tips tame things slightly and improve isolation, but the overall tonality still feels thin. I personally preferred using my own narrow bore tips like the Final Audio Type-E, which helped tighten the low end and take the edge off the treble, resulting in a more balanced listen.

Since the FH-01 is bundled in the box, it felt only fair to compare them briefly. The FH-01 offers a clear and clean presentation that is largely neutral with a touch of added warmth. Vocals can sound slightly veiled at times, but the overall listen is easier and less fatiguing than the Cielo. Cymbals lack a bit of bite and the depth of stage is not particularly impressive, though the width is quite expansive. On busy tracks it can still sound congested, but the tuning is generally more pleasant and forgiving.

In fact, I found the FH-01 to be the more enjoyable listen of the two. Its warmer yet open character makes it easier to relax into, whereas the Cielo’s brighter and more mid-forward tuning demands more careful source pairing and tip selection. Of course, it’s important to remember that both sit firmly in the entry level bracket.

Is It Worth It?

The Flathead Audio Cielo is an interesting first step into the IEM space for a brand rooted in flathead earbuds. I genuinely appreciate the generous accessories and the philosophy behind it as a gateway product for existing Flathead fans. The modular angle with their bluetooth adapter also shows a clear direction in how they see their ecosystem evolving.

Sonically, however, the Cielo feels more niche. Its neutral bright, upper mid focused tuning and lightweight bass will not be for everyone. It requires tip rolling and perhaps some source matching to get the best out of it. If you are already knee deep in the Flathead Audio lineup and want to complete the collection, the 40USD Cielo does make sense as part of that journey.

Otherwise, you might honestly find yourself reaching for the bundled FH-01 more often, inadvertently entering the flathead rabbit hole.