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If you want audiophile-grade sound from true wireless in-ear earbuds you can use every day, choose ICESOMNUS Sabbat E16; if you need to turn an airplane's 3.5mm seat-back jack into a Bluetooth signal for one or two pairs of headphones, choose Avantree Relay & SoundJet.
These two look like they belong in the same shopping cart, but they solve completely different problems. One is a music-first pair of earbuds built around a hybrid driver setup. The other is a tiny transmitter you plug into an AUX port on a plane. Picking the wrong one means you either carry an adapter you can't use, or you fly with earbuds that can't touch the seat-back screen. Here's how I'd decide.
• ICESOMNUS Sabbat E16 — biggest strength: A coaxial dual-driver design (dynamic driver plus balanced armature) tuned for a wide, detailed soundstage, with Bluetooth 5.2 and Qualcomm aptX.
• ICESOMNUS Sabbat E16 — biggest trade-off: It's a listening device only. It has no 3.5mm jack and can't act as a transmitter, so it won't help you with wired in-flight audio on its own.
• Avantree Relay & SoundJet — biggest strength: It converts a 3.5mm AUX output into Bluetooth 5.3 audio and can feed two headphones at the same time — the classic "share a movie on a long flight" fix.
• Avantree Relay & SoundJet — biggest trade-off: It's a single-purpose travel accessory. It won't work with phones, car stereos or hearing aids, and it doesn't play audio by itself.
• Who each is for: Buy the Sabbat E16 if you want better everyday wireless sound. Buy the Avantree Relay & SoundJet if you already own Bluetooth headphones and want to use them on a plane.
The Sabbat E16 is the "music lover's earbud" of this pair. Its whole pitch is inside the shell: a coaxial acoustic architecture that pairs a 10mm balanced armature driver with a dynamic driver. In plain terms, the dynamic side handles the low end and the balanced armature handles vocals and fine detail. That's the kind of setup people chase when they want a wider, more layered soundstage than a single-driver earbud typically gives. The spec sheet backs the ambition: 20Hz–20kHz frequency range, 93dB sensitivity at 1kHz/1mW, and a hybrid impedance figure split between the woofer and tweeter.
The wireless side is equally straightforward. Bluetooth 5.2 with Qualcomm aptX, plus AAC and SBC support, covers music, movies and everyday listening, and the rated range is about 10 meters. Latency is listed at 40ms, which matters if you watch video and hate lip-sync drift. For calls, Qualcomm's CVC8.1 noise reduction is on board, and the listed controls include active noise cancellation plus voice control and physical buttons — useful when your hands are full.
Battery is where it gets practical. ICESOMNUS lists over 6 hours per charge (one field pegs average life at 8 hours) and up to 30 hours with the case, with a 400mAh case battery and 40mAh in each earbud. The case charges over USB-C in roughly an hour, and — a nice touch at this level — it supports Qi wireless charging. Auto-pairing on opening the case means you're listening almost instantly, and the rounded-tip in-ear shape is meant for long sessions.
Who should buy it: Anyone who wants their money to go into sound quality and battery convenience — commuters, students, remote workers, and people who mostly listen on their own device and rarely touch an airplane seat-back screen.
Who should skip it: Frequent flyers who want to use wired-only in-flight entertainment without carrying extra gear, and anyone who needs a transmitter rather than earbuds. There's no 3.5mm jack here, so the E16 can't be plugged into an armrest.
The Avantree Relay & SoundJet R1 is a specialist, and it's honest about it. You plug it into a 3.5mm AUX jack — the one on an airplane seat-back, for example — and it broadcasts that audio over Bluetooth 5.3 using Qualcomm's premium chipset with aptX Adaptive and aptX HD. That's the entire point: the plane's screen stays wired, but your ears don't.
The feature that sells it is dual-headphone support. Two Bluetooth headphones can connect at once and stay synced, so you and a travel companion can watch the same movie together without splitting a cheap pair of airline buds. It's compatible with AirPods, Bose and Bluetooth headphones generally, and Avantree explicitly notes it is not compatible with phones, car stereos or hearing aids — so don't buy it as a general-purpose transmitter for your TV or stereo.
Play time is listed at up to 25 hours of continuous use, which comfortably covers long-haul flights. LED indicators show connection status, and onboard buttons handle pairing and volume, so you're not digging through menus mid-flight. It's lightweight and pocket-sized, marketed as a travel essential for flights and gym sessions — small enough to live in a carry-on pouch and forget about until you need it.
Who should buy it: Travelers who already own good Bluetooth headphones and want to use them with in-flight entertainment, especially couples or families who want to share one screen. Also a sensible pick for gym-goers with a 3.5mm-equipped machine.
Side-by-Side: Which Should You Choose?
• Best for sound quality and daily listening → ICESOMNUS Sabbat E16. The coaxial dual-driver design, aptX support and 20Hz–20kHz range are aimed squarely at music.
• Best for airplane entertainment → Avantree Relay & SoundJet. It exists to bridge a 3.5mm seat-back jack to Bluetooth 5.3.
• Best for sharing audio with a partner → Avantree Relay & SoundJet. Two headphones at once is a feature the E16 simply doesn't have.
• Best battery story → ICESOMNUS Sabbat E16. Up to 30 hours total with the case, plus USB-C and Qi wireless charging, versus 25 hours of continuous use from the adapter.
• Best for calls and video → ICESOMNUS Sabbat E16. CVC8.1 noise reduction, active noise cancellation and a 40ms low-latency figure are all listed.
• Best for travel-bag minimalism → Avantree Relay & SoundJet. It's pocket-sized and does one job extremely well.
• Best if you want earbuds at all → ICESOMNUS Sabbat E16. The Avantree doesn't produce sound on its own; it needs your headphones.
• Best if you already own AirPods or Bose headphones → Avantree Relay & SoundJet. It's built to work with what's already in your bag.
If I had to pick one, I'd buy the ICESOMNUS Sabbat E16. It's the product that earns its place in your pocket every single day — hybrid drivers, aptX, ANC, a 30-hour case and wireless charging are a lot of daily usefulness in one package, and it works the moment you open the lid. The Avantree Relay & SoundJet is excellent at what it does, but it's a situational tool: brilliant on a plane, useless in your living room. If your travel calendar is full and you already love your current Bluetooth headphones, flip that recommendation and get the adapter instead. Check the current price on Amazon for whichever one fits your week — that's the deciding factor I can't settle for you.
For wired in-flight entertainment, the Avantree Relay & SoundJet. It plugs into a 3.5mm AUX jack and streams to up to two Bluetooth headphones over Bluetooth 5.3. The Sabbat E16 has no 3.5mm jack, so it can't connect to a seat-back port directly.
No. The Relay & SoundJet is a transmitter only — it doesn't play audio by itself and needs your own Bluetooth headphones. The Sabbat E16 is a complete listening device with its own drivers, battery and charging case.
Yes. ICESOMNUS lists a 400mAh charging case that supports Qi wireless charging as well as USB-C, with a charge time of roughly 60 minutes. Playback is rated over 6 hours per charge and up to 30 hours with the case.
No. Avantree states it is not compatible with phones, car stereos or hearing aids. It's designed for 3.5mm AUX sources such as airplane seat-back systems, and it works with AirPods, Bose and other Bluetooth headphones.
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