TRN Mermaid Hybrid IEMs Review
A four-driver hybrid IEM with a 10mm glass diaphragm dynamic driver, a Knowles 33518 balanced armature and two 6mm planar drivers per side, listed from $199.99 in Purple or Green. It suits buyers who want 32Ω±15% and 109dB/mW on the page.
Our verdict
Targets buyers who want a four-driver hybrid IEM from $199.99 with listed impedance, a sensitivity figure that names its reference and a choice of 3.5mm or 4.4mm termination. Look elsewhere if you need a frequency response range or a measurement from someone other than the store. The main caveat is that the near zero distortion claim sits beside a THD+N figure of ≤1%.
- Best for
- Those choosing a four-driver hybrid IEM with two planar drivers and a choice of 3.5mm or 4.4mm termination.
- Skip if
- You need a listed frequency response range or an outside measurement.
Why 3.5/5: The store's own terms contradict each other and no independent test of this model was checked for this review; those two points hold the rating back.
TRN's Mermaid carries four drivers in each shell: a 10mm dynamic driver with a glass diaphragm, a Knowles 33518 balanced armature and two 6mm planar magnetic drivers, per the page. It is listed from $199.99 in two colors. The specification section gives 32Ω±15%, 109dB/mW and THD+N of ≤1%, with a 0.78mm 2-pin connector.
Specifications
| Spec | Page says |
|---|---|
| Drivers per side | 1DD+1BA+2 Planar |
| Dynamic driver | 10mm dual-magnetic, PU edge suspension, glass dome diaphragm |
| Balanced armature | Knowles 33518 |
| Planar drivers | Two 6mm self-developed, titanium-coated diaphragms |
| Impedance | 32Ω±15% |
| Sensitivity | 109dB/mW |
| THD+N | ≤1% |
| Connector type | 0.78mm 2-pin |
| Termination plug | 3.5mm/4.4mm |
| Cable | 4-strand oxygen-free copper, silver-plated |
| Colors | Mermaid Purple and Mermaid Green |
Options and pricing
Four options are listed: Mermaid Purple 3.5mm and 4.4mm at $199.99 each, and Mermaid Green 3.5mm and 4.4mm at $229.99 each, all orderable when the page was read. The page text gives no reason for the higher Green price, and it names the colors Jade Shadow Green and Ink Night Purple. The cable is a 4-strand oxygen-free copper silver-plated cable on 0.78mm 2-pin connectors, with the plug set by the option.
How it compares
The HarmonicDyne P.D.1 Planar Driver HiFi In-Ear Earphones IEMs are $199 with a planar driver in the name, the KEFINE Arnar 1 BA+1 Planar Driver In-Ear Earphones are $189 with 1 BA+1 Planar Driver in the name, and the AFUL Performer5 / Performer 5 1DD + 4BA IEMs start at $210.99 with 1DD + 4BA in the name, against $199.99 here for 1DD+1BA+2 planar. The Mermaid suits buyers who want a dynamic driver, an armature and planar drivers together; the Performer 5 suits those who want four armatures and lists no planar driver in its name.
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
- Four drivers per side: 10mm glass diaphragm dynamic, Knowles 33518 armature and two 6mm planar, per the page
- Specification section lists 32Ω±15%, 109dB/mW with its mW reference, THD+N of ≤1% and the connector type
- 0.78mm 2-pin connectors with 3.5mm or 4.4mm termination by option
- Two colors, Mermaid Purple and Mermaid Green, each with both plug options
- Planar diaphragms described as titanium-coated and the dynamic driver as dual-magnetic with PU edge suspension, per the page
Worth noting
- Mermaid Green is $229.99 against $199.99 for Mermaid Purple, and the page text gives no reason for the gap
- The page text gives no frequency response range
- The page lists near zero distortion as a feature, while the page text gives one distortion figure, THD+N of ≤1%
- The page text gives no shell weight, cable length or ear tip list
Questions before you buy
What drivers does the TRN Mermaid use?
The page lists one 10mm dual-magnetic dynamic driver with a glass diaphragm, one Knowles 33518 balanced armature and two self-developed 6mm planar magnetic drivers on each side.
What does the Mermaid list for impedance and sensitivity?
The specification section gives 32Ω±15% impedance and 109dB/mW sensitivity, plus THD+N of ≤1%. The page text gives no frequency response range.
Why do the two colors have different prices?
Mermaid Purple is $199.99 and Mermaid Green is $229.99 in both the 3.5mm and 4.4mm versions. The page text gives no reason for the difference.
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
- TRN Mermaid 1DD+1BA+2Planar Drivers In-Ear Monitor product page: specs, options and price (the buy buttons go there)Specs, 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 near zero distortion among its features, while its specification section gives THD+N of ≤1%; the page text gives no frequency response range.
- Mermaid Green is $229.99 and Mermaid Purple $199.99 for the same 3.5mm and 4.4mm choices; the page text gives no reason for the gap.
- Sound claims about vocals, imaging and tonality are the page's wording; the page text gives no graph or measurement.
- 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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