We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-18 · 7 min read · Independent comparison
If you want to turn any airplane seat-back screen or gym treadmill into a wireless listening session with your own headphones, choose Avantree Relay & Voyager; if you need true wireless earbuds with adaptive noise cancelling, lossless-grade audio and real-time translation, choose EarFun Air Pro 4+.
• Avantree Relay & Voyager — biggest strength: It's a tiny Bluetooth 5.3 transmitter with a Qualcomm chipset, aptX Adaptive and aptX HD support, plus an OLED display for monitoring connections and battery — a purpose-built bridge from a 3.5mm AUX jack to your existing headphones.
• Avantree Relay & Voyager — biggest trade-off: It's a one-job device. It works only with the 3.5mm AUX output and Bluetooth headphones, and it explicitly doesn't work with phones, car stereos or hearing aids.
• EarFun Air Pro 4+ — biggest strength: A complete listening system in one box — hybrid dual drivers, Qualcomm QCC3091 with Snapdragon Sound and aptX Lossless, up to 50dB adaptive ANC, 6-mic AI call clarity, and app-based AI translation across 100+ languages.
• EarFun Air Pro 4+ — biggest trade-off: It's earbuds, not an adapter. It can't take an analog signal from an airplane jack or any wired source, and its headline features (translation, ANC tuning, codec control) depend on the EarFun Audio App.
• Who each is for: Pick Avantree if you already own great wired-style headphones and want them to work wirelessly on flights and gym equipment. Pick EarFun if you want one self-contained pair of earbuds that handles music, calls, noise and travel translation on its own.
The Relay & Voyager solves one very specific, very common travel annoyance: you're on a plane, there's a screen in front of you, and the only way to hear it is a 3.5mm jack and whatever cheap headset the airline hands out. This adapter plugs into that AUX port and rebroadcasts the audio over Bluetooth 5.3 to the headphones you actually like. Avantree has been in the wireless audio business for two decades, and that shows in the spec sheet — a premium Qualcomm chipset, aptX Adaptive and aptX HD for high-fidelity transmission, and aptX Low Latency for keeping audio and video in sync when your listening device supports it.
The details are thoughtfully travel-oriented. There's an OLED display, which is unusual in this category and genuinely useful — you can see connection status and battery level at a glance instead of guessing from a blinking light. Built-in controls let you adjust volume, pair, reconnect and clear pairing history without touching your phone. The LED indicators back up the display. And it's compact and pocket-sized, so it disappears into a seat-back pocket or gym bag without adding bulk.
The honest limitations matter just as much. The Relay & Voyager is designed for 3.5mm AUX input and Bluetooth headphone output — that's it. Avantree states plainly that it isn't compatible with phones, car stereos or hearing aids, so don't buy it hoping it'll add Bluetooth to your older car or your TV's headphone jack. It also only makes sense if you already own Bluetooth headphones you like; it's an accessory, not a sound system. Buy it if you fly often, use gym equipment with analog audio outputs, or want AirPods, Bose or other Bluetooth headphones to work with in-flight entertainment. Skip it if you want earbuds, noise cancelling, or a device that works with phones and cars.
The EarFun Air Pro 4+ is a different animal entirely — it's the whole package. The core of it is a hybrid driver system pairing a 10mm composite dynamic driver with a lightweight balanced armature, set at an 11-degree angle alignment that EarFun says reduces high-frequency attenuation. Translated from spec-speak: you get a two-way design where one driver handles the low end and the other handles detail and treble, which is exactly the approach you want if you care about a clean, layered soundstage rather than a single-driver compromise.
On the wireless side it runs Qualcomm's QCC3091 SoC and is certified for Snapdragon Sound with aptX Lossless, plus LDAC, LC3 and LE Audio support. That's a broad codec spread — it means the earbuds can scale up with a good source device instead of capping your audio quality. The frequency range is listed at 20Hz–40kHz, which is wider than the standard 20kHz ceiling and is the kind of figure you see attached to hi-res claims.
Buy it if you want one device for music, calls, commuting noise and travel translation, and you're willing to use the EarFun Audio App to unlock the full feature set. Skip it if your main need is getting audio out of an airplane seat-back jack — the Air Pro 4+ is wireless-only with no jack, so it can't do that job at all.
Side-by-Side: Which Should You Choose?
• Best for airplane seat-back entertainment → Avantree Relay & Voyager. The 3.5mm AUX input is the entire point; it turns a wired jack into a Bluetooth stream.
• Best for noise cancelling → EarFun Air Pro 4+. Up to 50dB adaptive hybrid ANC, tuned automatically to your surroundings.
• Best for call clarity → EarFun Air Pro 4+. Six AI-enhanced ENC microphones versus no mic array on the Avantree adapter.
• Best for using headphones you already own → Avantree Relay & Voyager. It's compatible with AirPods, Bose and other Bluetooth headphones, so your existing pair becomes the star.
• Best for highest-resolution wireless audio → EarFun Air Pro 4+. aptX Lossless via Snapdragon Sound certification, plus LDAC, LC3 and LE Audio.
• Best for gym equipment with analog audio → Avantree Relay & Voyager. Same AUX-to-Bluetooth trick, and it's small enough to live in a gym bag.
• Best for travel translation → EarFun Air Pro 4+. Real-time and face-to-face translation across 100+ languages through the app.
• Best for a one-and-done purchase → EarFun Air Pro 4+. It's a complete listening solution; the Avantree is an add-on for people who already have the rest.
For most people, I'd buy the EarFun Air Pro 4+. In my opinion it's the more versatile purchase by a wide margin: you get the dual-driver audio architecture, adaptive ANC, a six-mic call system, wide codec support and translation in a single product, and it works everywhere — commute, flight, calls, gym. The Avantree Relay & Voyager is excellent at what it does, but what it does is narrow, and it only pays off if you already own Bluetooth headphones you love and specifically want them to work with airplane and gym analog outputs. If that's your situation, the Avantree is the smarter buy and I'd recommend it without hesitation. If you're starting from nothing, buy the EarFun. Check the current price on Amazon before deciding, since the value math changes depending on what you already own.
Yes, that's arguably its ideal use case. It's built to work with AirPods, Bose and other Bluetooth headphones, letting you use them with a plane's 3.5mm AUX jack. Just remember it won't work with phones, car stereos or hearing aids.
No. The Air Pro 4+ is wireless-only with no headphone jack, so it can't plug into seat-back entertainment. For that job you need the Avantree Relay & Voyager, which accepts 3.5mm AUX input.
On paper, the EarFun Air Pro 4+ goes further: hybrid dual drivers, a 20Hz–40kHz range, aptX Lossless, LDAC and Snapdragon Sound certification. The Avantree is a transmitter — its ceiling is set by the aptX Adaptive/HD stream and the headphones you connect to it.
You can listen without it, but you'd be leaving features on the table. Translation, ANC behaviour and codec control all run through the EarFun Audio App, and EarFun advises keeping the app updated to the latest version.
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