If you want a dedicated, long-haul travel companion with an integrated battery and airplane-specific design, choose Avantree Relay; if you need a versatile, low-latency transmitter for home office setups that powers directly from your desk, choose Yunseity LE502.
• Avantree Relay: Its biggest strength is the self-contained 25-hour battery and dual-link capability for sharing flight entertainment without wires; its trade-off is the lack of a microphone, making it unusable for calls or voice communication.
• Yunseity LE502: Its biggest strength is the direct USB power draw and advanced aptX Adaptive support optimized for low-latency video sync in a home environment; its trade-off is the absence of a built-in battery, requiring it to stay tethered to a power source.
• Who it's for: The Relay is for travelers and those prioritizing portability on flights, while the LE502 is for professionals seeking crystal clear calls and stable audio streams for work from home environments.
The Avantree Relay is engineered specifically for the traveler who refuses to compromise on audio quality during long-haul flights. Its most defining feature is the ability to connect two pairs of Bluetooth headphones simultaneously to a single 3.5mm audio source, such as an airplane entertainment screen. This "Share In-Flight Audio" capability means you and a travel partner can enjoy the same movie or music feed without needing a single pair of wired earbuds to split the signal. The device runs on a built-in Lithium-Polymer battery that promises up to 25 hours of playtime, which is substantial enough to cover even the longest international routes without needing a recharge mid-flight.
Design-wise, the Relay feels purpose-built for mobility. It weighs just 4.4 grams and comes in a durable Acrylonitrile Butadiene Styrene (ABS) enclosure that resists the bumps of carry-on luggage. The interface is simple, relying on touch controls and a clear battery indicator so you always know how much juice remains. However, this focus on passive listening comes with a hard limitation: the unit has no microphone. It is strictly a transmitter designed to send audio from a source to your headphones. If your work from home routine involves taking conference calls or using noise-canceling features that require two-way audio, this device will not work for you. It cannot receive audio, nor can it be used for phone calls, TVs, hearing aids, or musical instruments.
This makes the Avantree Relay the ideal choice for the frequent flyer who wants to share entertainment with a spouse or child without fighting over one pair of wireless buds. It is also perfect for gym-goers who want to stream from a machine's aux jack without worrying about cables getting tangled. But for anyone looking for sleep headphones for work from home that include call functionality, or for someone needing to broadcast their own voice, the Relay is a dead end. It is a specialized tool for high-quality, one-way audio distribution where battery life and portability are the top priorities.
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-25 · 6 min read · Independent comparison
The Yunseity LE502 takes a different approach by focusing on stability and integration into a fixed workspace. As a Bluetooth 5.3 transmitter, it leverages newer connectivity standards to ensure lower power consumption and a more robust connection than older models. It supports dual-stream transmission, meaning you can connect two Bluetooth speakers or headphones at the same time, both utilizing the same codec for synchronized audio. This is particularly useful for a home office setup where you might want to listen to a meeting on your headphones while having a speaker broadcasting the audio in the room, or simply for managing multiple devices without switching them constantly.
What sets the LE502 apart in a professional context is its power architecture and latency handling. Unlike the Relay, which relies on internal batteries, the LE502 draws power directly via a USB 2.0 connection. This eliminates the anxiety of a dying battery during an important presentation or a long work session. It supports aptX Adaptive, which dynamically adjusts the audio bitrate and latency based on the content, ensuring that video syncing remains tight. The device includes visual indicators that light up to show when aptX Adaptive encoding is active, giving you confidence that you are receiving the highest quality signal available. It is driver-free and compatible with Windows 7, 8, 10, and various other systems, making it a plug-and-play solution for almost any computer setup.
However, because it requires constant AC/DC power through USB, it is not a portable device you can throw in a bag for a trip. It is anchored to your desk or TV stand. This makes it less suitable for travel but ideal for anyone needing crystal clear calls and stable sound for work from home scenarios. The dual-stream capability allows for flexible audio management, whether you are monitoring background music while on a call or sharing audio across a large room. If your primary concern is maintaining a consistent, low-latency connection for video content or professional communication without the hassle of charging a separate battery, the LE502 is the superior engineering choice.
• Best for Battery Life and Travel → Avantree Relay, thanks to its 25-hour onboard capacity and lightweight design.
• Best for Work From Home Stability → Yunseity LE502, as it draws continuous power and avoids battery anxiety during critical meetings.
• Best for Dual-Device Sharing → Both support dual links, but the Relay is optimized for flight screens while the LE502 excels in home speaker/headphone pairs.
• Best for Low Latency Video Sync → Yunseity LE502, leveraging BT 5.3 and aptX Adaptive for real-time audio-visual alignment.
• Best for Portability → Avantree Relay, weighing only 4.4g and fitting easily into a pocket or carry-on.
• Best for Call Capabilities → Neither product natively supports microphones or two-way audio, so neither is ideal for hands-free calling without external adapters.
• Best for Visual Feedback → Yunseity LE502 offers status lights for coding types, whereas the Relay uses a simple battery indicator.
• Best for Power Flexibility → Yunseity LE502 works wherever you have a USB port, while the Relay requires pre-charging before every use.
In my opinion, for a serious work from home setup, I would choose the Yunseity LE502. The ability to run continuously off a USB connection ensures that I never have to worry about the audio cutting out due to a depleted battery during a crucial client call. The BT 5.3 technology and aptX Adaptive support provide the stability needed for video conferencing, and the dual-stream feature adds a layer of flexibility that the Relay simply cannot match in a stationary environment. While the Avantree Relay is a marvel of portable engineering, its lack of microphone and reliance on internal power make it a niche travel gadget rather than a daily driver for productivity. The LE502 feels like the more robust, future-proof investment for anyone building a permanent audio station at their desk.
No, the Avantree Relay is a transmitter-only device with no microphone and cannot handle phone calls or two-way audio communication.
No, the Yunseity LE502 draws power directly from a USB 2.0 connection, so it does not have an internal battery and does not need to be charged separately.
Both support aptX Adaptive, but the Yunseity LE502 includes specific status lights to confirm the codec is active, which helps verify low-latency performance for video.
Yes, both devices support dual-link connections, allowing two pairs of headphones to connect to one source, though the Relay is specifically marketed for this airline use case.
As an Amazon Associate I earn from qualifying purchases.
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.
When you buy through links on this page, we may earn a commission from qualifying purchases at no extra cost to you.
Amazon and the Amazon logo are trademarks of Amazon or its affiliates. This site is an independent third-party review and is not affiliated with, endorsed by, or sponsored by Amazon or the product brands mentioned.