We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-20 · 7 min read · Independent comparison
If you want a pocket-sized Bluetooth DAC/amp that turns wired headphones into a wireless hi-res rig with a nostalgic cassette-player vibe, choose FiiO /Snowsky Retro Nano; if you need an in-flight Bluetooth transmitter that lets two people share one airplane screen at the same time, choose Avantree Relay & SoundJet. These two look like they occupy the same shelf, but they solve completely different problems. One is for listening to your own music your way; the other is for watching the airline's movie with a friend.
• FiiO /Snowsky Retro Nano — biggest strength: a real Bluetooth USB DAC/amp with LDAC, aptX Adaptive and aptX LL, dual high-performance DACs, and up to 220mW balanced output through a 4.4mm jack.
• FiiO /Snowsky Retro Nano — biggest trade-off: it's a personal listening device, not a shareable one — it doesn't broadcast audio to two sets of headphones for a shared screen.
• Avantree Relay & SoundJet — biggest strength: pairs two Bluetooth headphones or AirPods at once and runs up to 25 hours per charge, built specifically for airplane entertainment.
• Avantree Relay & SoundJet — biggest trade-off: it's a transmitter only. It is explicitly not for TVs, phones, hearing aids or musical instruments, and it won't pair with phones or tablets.
• Who each is for: FiiO /Snowsky Retro Nano is for the person who wants to upgrade their own wired headphones wirelessly and tweak the sound; Avantree Relay & SoundJet is for couples or travel partners who want to watch the same seatback screen together.
The Retro Nano is, at its core, a Bluetooth USB DAC and amp. It takes a wireless signal and feeds it into your wired headphones through either a 3.5mm unbalanced or a 4.4mm balanced output. That balanced output is the headline for anyone with demanding wired headphones: two high-performance DACs push a balanced output power of up to 220mW, which is a meaningful figure for a device this small. It supports LDAC, aptX Adaptive and aptX LL, so you get high-quality codecs as well as a low-latency option — the latter matters if you're watching video and don't want the audio trailing the picture.
Battery is handled smartly too. It runs on a detachable, rechargeable 3.7V lithium battery rated for up to 7.5 hours of continuous playback, and because the battery is replaceable, a drained cell doesn't mean a dead device. The package includes a cable, it weighs about 0.11 kg, and it carries a 1-year warranty.
Buy it if you own wired headphones, want to cut the cord without dropping to mediocre sound, and enjoy tuning your own signature. Skip it if your goal is to share audio with a second person on a plane — that's simply not what this device is built to do.
Avantree Relay & SoundJet: Who It's For
The Avantree Relay & SoundJet R1 is a single-purpose tool, and that's a compliment. It's a premium airplane Bluetooth adapter built on a Qualcomm chipset, and its defining feature is that it pairs two Bluetooth headphones or two sets of AirPods simultaneously. That means two people can watch the same in-flight entertainment side by side, each with their own volume and their own comfort — no splitter cable dangling between seats.
The audio side is handled by Qualcomm aptX Adaptive, which Avantree frames around balanced sound and dependable wireless performance during a flight. It's a transmitter, so audio goes in through a 3.5mm AUX connection (the airline's headphone jack) and out over Bluetooth. Its supported standard is aptX Adaptive, it's a two-channel device, and it's powered by its own battery. That battery is rated for up to 25 hours of listening on a single charge, which comfortably covers long international flights and frequent flyers who don't want to think about charging mid-trip.
Here's the part that matters most before you buy: it is not for TVs, hearing aids or musical instruments, and it will not pair with phones or tablets. This is not a general-purpose Bluetooth transmitter you can repurpose around the house. It's built for airplanes, and it's excellent at that job — but if you buy it expecting to connect your TV, you'll be disappointed.
Side-by-Side: Which Should You Choose?
• Best for upgrading wired headphones wirelessly → FiiO /Snowsky Retro Nano. Balanced 4.4mm output plus LDAC, aptX Adaptive and aptX LL support.
• Best for sharing one airplane screen with two people → Avantree Relay & SoundJet. It pairs two Bluetooth headphones or AirPods at the same time.
• Best for long trips without charging → Avantree Relay & SoundJet. Up to 25 hours of playtime on a single charge versus 7.5 hours on the Retro Nano.
• Best for battery longevity over years → FiiO /Snowsky Retro Nano. Its 3.7V lithium battery is detachable and replaceable, so a worn cell doesn't retire the device.
• Best for sound customization → FiiO /Snowsky Retro Nano. 8 retro-inspired sound effects plus DIY tuning via app and web interface.
• Best for output power → FiiO /Snowsky Retro Nano. Up to 220mW balanced output from dual high-performance DACs.
• Best for plug-and-play simplicity on a flight → Avantree Relay & SoundJet. Wired 3.5mm AUX in, Bluetooth out, no tuning required.
• Best for a device with some character → FiiO /Snowsky Retro Nano. The cassette-player design and interactive retro UIs are a deliberate style choice.
In my opinion, the right pick comes down entirely to what you actually do with audio. If you own wired headphones and want to enjoy them untethered — with strong codec support, real balanced output power, and the freedom to tune the sound yourself — I'd buy the FiiO /Snowsky Retro Nano. It does more, and it does it in a way you can personalize. The Avantree Relay & SoundJet is the better choice only if your specific need is sharing in-flight entertainment with a second person, where its two-headphone pairing and 25-hour battery make it the obvious tool. Neither is a compromise for the other's job — they're just different jobs. Check the current price on Amazon before you decide, since that's the one variable this comparison can't settle for you.
For sharing a seatback screen with two people, the Avantree Relay & SoundJet wins — it pairs two Bluetooth headphones at once and lasts up to 25 hours. The Retro Nano is a personal DAC/amp, not a two-headphone transmitter, so it fits solo listening rather than shared screens.
No. Avantree states it is not compatible with TVs, hearing aids or musical instruments, and it does not pair with phones or tablets. It's a Bluetooth transmitter with a 3.5mm AUX input, designed for airplane entertainment.
Yes. It has both a 3.5mm unbalanced and a 4.4mm balanced output, so it can drive wired headphones while receiving audio over Bluetooth using LDAC, aptX Adaptive or aptX LL.
The Avantree Relay & SoundJet is rated for up to 25 hours per charge, while the FiiO /Snowsky Retro Nano is rated for up to 7.5 hours. The Retro Nano offsets that with a detachable, replaceable battery, so it can be refreshed rather than replaced.
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