Moondrop COSMO Planar Headphones Review
A headphone with a 100mm planar magnetic driver at $999, tagged open back by the store, with 15Ω±15% impedance and 100dB/Vrms sensitivity per the page. It suits listeners who want a 4.4mm balanced cable and a 3.5mm single-ended adapter.
Our verdict
The COSMO is for buyers who want a planar magnetic headphone with stated impedance and sensitivity, an open back per the store's tag, and both a 4.4mm balanced cable and a 3.5mm adapter at $999. Look elsewhere if you need a stated weight, cable length or ear pad detail. The sound wording is the page's own. Every spec figure here is the store's own, as no independent test was checked for this review.
- Best for
- Listeners who want a 100mm planar magnetic headphone with a 4.4mm balanced cable.
- Skip if
- You need a stated weight, cable length or ear pad detail.
Why 3.5/5: Held back because no independent test was checked for this review, which leaves every spec figure resting on the store's page, and because the store's own terms contradict each other.
Moondrop's COSMO is a headphone with a 100mm planar magnetic driver that the store tags as open back, listed at $999. The page gives 15Ω±15% impedance, 100dB/Vrms sensitivity and a 13Hz-58kHz free-field range, and describes an ultra-thin nanoscale diaphragm with an etched pure silver circuit. It lists universal dual 3.5mm plugs, a 4.4mm balanced cable and a 3.5mm single-ended adapter.
Specifications
| Spec | Page says |
|---|---|
| Driver | 100mm planar magnetic driver |
| Diaphragm | Ultra-thin nanoscale diaphragm, approximately 500nm thick |
| Magnets | N52 magnet array |
| Impedance | 15Ω±15% |
| Sensitivity | 100dB/Vrms |
| Frequency range | 13Hz-58kHz(Free-Field) |
| Effective frequency range | 20Hz-20kHz |
| Plugs | Universal dual 3.5mm plugs |
| Cable | High-purity single-crystal copper cable, 4.4mm balanced termination |
| Adapter | 3.5mm single-ended adapter |
| Target response | Moondrop VDSF |
| Named technologies | FDT (the page's Full Drive Technology); TBT (tension-balanced technology) |
| Design | Open back, per the store's tag |
Options and pricing
One option is listed, COSMO, at $999, and it was orderable when the page was read. The option name gives no color, cable or plug choice. The page says the headphone comes bundled with a high-purity single-crystal copper cable with a 4.4mm balanced termination, and its feature list names a 3.5mm single-ended adapter and universal dual 3.5mm plugs. The page text gives no cable length.
How it compares
The Moondrop PARA 2 100mm Patented Planar Driver Hi-Fi Headphone is $499.99 and names a 100mm planar driver from the same maker. The FiiO FT7 106mm Open Back Planar Magnetic Driver Headphone is $699.99 with a 106mm planar driver, and the DUNU ARASHI 100mm Planar Magnetic Driver Headphones are $1,399.99 with a 100mm planar magnetic driver; its spec line reads Sensitivity up to 97dB/mW (113dB/Vrms). At $999 the COSMO sits between the FT7 and the ARASHI on price, and the PARA 2 suits buyers with a lower budget.
Shipping, returns and warranty
HiFiGO sells from hifigo.com and says every order leaves its warehouse in China, usually 1-3 business days after it is placed, and says its delivery times are estimates, not promises. Its shipping policy gives the United States 1-2 weeks (about 10 days on average) by Priority and 6-10 days by Premium, both with duties and taxes prepaid by the store; Canada 2-3 weeks; the United Kingdom 1-2 weeks; and Australia 10-15 days. Express couriers (DHL, UPS, FedEx) take 3-7 days, but then the buyer pays any duties and taxes. No shipping page names New Zealand, PO boxes are not accepted, and the free-shipping thresholds differ between the store's own pages, so check the cart. One of its two shipping pages adds that a lost parcel on an order above $50 gets only a 50% refund. A US buyer reported a $40 tariff charge in August 2025, after which HiFiGO said it had added a customs notice at checkout.
Read the return terms before you order. The homepage advertises 7-day returns. Both of HiFiGO's policy pages offer a 7-day dead-on-arrival cover (a replacement or a full refund, with the return postage refunded) and also describe 30-day returns, but a request made 7 to 30 days after delivery loses 30% of the MSRP as a restocking fee (10% more if the packaging is incomplete), plus shipping both ways and duties, and the FAQ on the same pages says there is no refund or exchange once 7 days have passed. One version recommends reselling an opened product locally. Custom IEMs and custom cables cannot be returned, no return address is published, and buyers describe sending items back to China.
HiFiGO's warranty runs one year from the order date for parts and labor; its policy names desktop DACs and amps, IEMs and dongles at one year and gives cables and adapters three months. HiFiGO decides between repair and replacement, the buyer pays the shipping, and faulty items go back for service, not for a refund. Claims go to [email protected], the only contact the store lists: its pages name no company, street address or phone, and its terms are governed by the laws of China.
On Trustpilot, HiFiGO had 4.6 out of 5 from 378 reviews when we checked on 2026-10-28 (91% five-star, 5% one-star), and it had replied to about 75% of negative reviews; Trustpilot notes the store has not invited customers to review recently. The one-star reviews mostly concern the short return window and the deductions on returns, items listed in stock that turned out back-ordered, slow email support and a tariff charge on a US delivery in 2025. HiFiGO says its products are genuine and come in the brands' retail packaging; it does not claim to be an authorized dealer.
What we liked
- The page lists impedance (15Ω±15%), sensitivity (100dB/Vrms) and two frequency ranges, 13Hz-58kHz (Free-Field) and an effective 20Hz-20kHz.
- Both a 4.4mm balanced cable and a 3.5mm single-ended adapter are named.
- The page gives a diaphragm thickness of approximately 500nm and names its magnet array (N52).
- The page names the target response it says it follows: Moondrop VDSF.
Worth noting
- The page text gives no weight figure, although it says the plastic internal frame reduces the weight.
- The page text gives no cable length and no ear pad detail.
- Open back comes from the store's tag; the page text itself does not state the design.
- The two frequency ranges come with no stated measurement method beyond the Free-Field label on the first.
Questions before you buy
What driver does the Moondrop COSMO use?
The page lists a 100mm planar magnetic driver with an ultra-thin nanoscale diaphragm of approximately 500nm, a highly elastic pure silver etched circuit, an N52 magnet array and a dual-cavity high-frequency phase control waveguide.
What are its impedance, sensitivity and frequency range?
The page lists 15Ω±15%, 100dB/Vrms, a 13Hz-58kHz frequency range (Free-Field) and an effective range of 20Hz-20kHz. The page text gives no amplifier or output power requirement, although a feature line says easy driveability.
Which cable and plugs does the page list?
The page lists universal dual 3.5mm plugs, says the headphone comes bundled with a high-purity single-crystal copper cable with a 4.4mm balanced termination, and names a 3.5mm single-ended adapter. The page text gives no cable length.
Where does HiFiGO ship from, and how long does it take?
From its warehouse in China, usually 1-3 business days after the order. The shipping policy gives 1-2 weeks to the US by Priority (6-10 days by Premium), both with duties and taxes prepaid, 2-3 weeks to Canada, 1-2 weeks to the UK and 10-15 days to Australia. Express couriers take 3-7 days, but the buyer pays any duties.
Can I send it back if I change my mind?
HiFiGO gives 7 days to report an item that arrives dead, damaged or wrong. Its policy also describes 30-day returns, but requests 7 to 30 days after delivery lose 30% of the MSRP plus shipping both ways and duties, and the FAQ on the same page says no refund or exchange after 7 days. Ask [email protected] before you open the box.
What warranty does HiFiGO give?
One year from the order date for parts and labor, for faults in build or materials (the policy names desktop DACs and amps, IEMs and dongles; cables and adapters get three months). HiFiGO chooses repair or replacement, the buyer pays the shipping, and a faulty item is serviced rather than refunded. Claims go to [email protected].
Sources & verification
What this review is based on and the day we last read it. Specs and claims from the maker are the maker’s own; the verdict and the rating are ours.
From the store
- Moondrop COSMO Flagship 100mm Nanoscale Ultra-Thin Planar Driver Headphone product page: specs, options and priceSpecs, options and the listed priceRead October 28, 2026
- HiFiGO shipping policyShips from China in 1-3 business days; US 1-2 weeks by Priority or 6-10 days by Premium, duties prepaid; Express buyers pay dutiesRead October 28, 2026
- HiFiGO shipping and order tracking pageA second shipping text: Premium also for Canada and Australia, Canada free shipping from $99.99, lost-parcel rulesRead October 28, 2026
- HiFiGO refund policy7-day dead-on-arrival cover; 30-day returns minus a 30% restocking fee; its FAQ says no refund after 7 daysRead October 28, 2026
- HiFiGO warranty and refund policyWarranty by product class (1 year; cables and adapters 3 months); 30% fee for resealing an opened productRead October 28, 2026
- HiFiGO terms of serviceOperator named only as HiFiGo; governed by the laws of China; contact [email protected]Read October 28, 2026
Independent
- HiFiGO reviews on Trustpilot4.6 of 5 from 378 reviews (91% five-star, 5% one-star); the store has not invited reviews recentlyRead October 28, 2026
What we couldn’t verify
- The page lists 13Hz-58kHz(Free-Field) and an effective 20Hz-20kHz without saying how either was measured beyond the Free-Field label, and gives 100dB/Vrms with no stated test frequency.
- Claims with no proof: a diaphragm about 500nm thick, a patented drive technology (FDT), tuning to the Moondrop VDSF target response, sound wording on soundstage and details, and a top-model status the store title and page state without saying what it sits above.
- Open back appears only in the store's tag; the page text describes an open sound presentation but does not state the earcup design.
- HiFiGO's policy pages contradict each other: 30-day returns with a 30% restocking fee in one place, no refund or exchange after 7 days in the FAQ.
- HiFiGO's pages name no company, street address or phone number; the only contact given is [email protected].
Spotted an error or something out of date? Tell us and we’ll fix it and update the date.
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