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Our previous portable pick, the Mpow BH259A, has been discontinued, and we’ve replaced it with the 1Mii ML300. We also have a new pick for home use, the 1Mii B03.
Wireless headphones are great—until you want to use them with a source that lacks Bluetooth, such as an in-flight entertainment system or an older TV. A Bluetooth transmitter solves this problem by making any AV device with a headphone jack (or other type of audio output) compatible with Bluetooth. The best Bluetooth transmitter you can buy for use on the go is 1Mii’s ML300, while our favorite for connecting to your TV is 1Mii’s B03.
When paired with supported devices, this essential codec helps to nearly eliminate lip-sync lag while watching videos.
We considered only transmitters that can connect with at least two devices simultaneously.
We preferred models that make the pairing and switching processes as intuitive as possible.
We used test equipment to measure each transmitter’s latency, frequency response, and sound-output level to assess performance.
This small, portable transmitter sounds as good as any other model we tested, and it actually works as advertised, which isn’t a given in this category.
*At the time of publishing, the price was $22.
The 1Mii ML300 offers everything we want to see in a portable Bluetooth transmitter: a solid, 10-hour battery life; support for the aptX Low Latency Bluetooth codec (to improve the sync between audio and video); and the ability to pair to two sets of headphones at once. It matches the sound quality of the other portable models we tested and produces about the same amount of audio lag, but it’s easier to use. The ML300 is small and light enough for you to carry it to the gym or while traveling, and it comes with everything you need to connect to your audio source.
The B03 integrates easily into your existing home theater setup and offers the lowest latency of any transmitter we’ve tested.
If you’re looking for a more permanent setup to transmit audio wirelessly from your TV or another home audio device, go with 1Mii’s B03. Much like the ML300, the B03 supports aptX Low Latency, multi-device pairing, and a receiver mode. It’s better than other TV-based models because it has the lowest latency (aka lag) of any transmitter we’ve tested when paired with aptX Low Latency headphones, which helps to eliminate lip-sync issues when watching TV. The transmitter passes audio through to a soundbar (or other external speakers), and you can broadcast the Bluetooth signal while also listening from your TV. The 1Mii B03 is larger than the ML300 and lacks a battery, but we don’t think those drawbacks are huge concerns for a home-based transmitter.
This small, portable transmitter sounds as good as any other model we tested, and it actually works as advertised, which isn’t a given in this category.
*At the time of publishing, the price was $22.
The B03 integrates easily into your existing home theater setup and offers the lowest latency of any transmitter we’ve tested.
I’ve been reviewing all manner of things at Wirecutter, from phone cases and tablets to selfie sticks and barware, since 2014.
Wirecutter senior staff writer Brent Butterworth conducted lab measurements of all the transmitters we tested to make sure the devices reproduced the full range of sound and had no excess latency. Brent has 30 years of experience reviewing audio gear and is one of a very small number of journalists who are equipped to measure Bluetooth devices.
Bluetooth wireless headphones and earbuds are rapidly becoming the preferred choice in headphones, especially as more smartphone makers remove the headphone jack. But if you want to use your pair to listen to an audio source that doesn’t have built-in Bluetooth—such as an in-flight entertainment system, the equipment at the gym, or an older smart TV—you just can’t do it.
Bluetooth transmitters provide a solution to that problem, essentially adding Bluetooth to devices that lack it. They connect to the source via an audio cable and wirelessly broadcast the audio to your headphones or even to a Bluetooth speaker. Some models are small and portable, with a built-in battery, while others are designed to be stationary and used with your TV so that you can listen to what you’re watching without disturbing others or keep listening as you leave the room.
You can find a ton of Bluetooth transmitters, and most of them are relatively similar to one another in functionality, design, and price. Because they’re all so comparable, we focused our search on transmitters that included a few more-advanced features:
What are the different Bluetooth audio codecs and how much do they affect a device’s sound quality? (Hint: Not as much as you might think.)
Our initial research turned up 42 models across both the portable and home categories. We dismissed many for failing to hit all of the above criteria; some didn’t support aptX Low Latency, for example, or could pair to only one set of headphones at a time. Once we had narrowed down the list, we began hands-on testing of the remaining models (six portable and three stationary), first with a simple setup and then with more-advanced audio testing. For our summer 2021 update, we tested an additional five transmitters—three portable and two stationary.
We used the following criteria to evaluate each transmitter:
This small, portable transmitter sounds as good as any other model we tested, and it actually works as advertised, which isn’t a given in this category.
*At the time of publishing, the price was $22.
The 1Mii ML300 is the best portable Bluetooth transmitter because it matches the audio features of every other device we tested and actually does everything it claims to do, which wasn’t always the case with other transmitters. It pairs with two sets of headphones at once, allows you to toggle it to be a Bluetooth receiver, and supports aptX Low Latency for improved audio and video sync. And its flat design, light weight, and decent battery life make it easy to use on the go.
Performance is key among these devices, and the 1Mii is as good as any other transmitter. In our latency tests, when using the SBC codec, we found that the lag was 139 milliseconds (the average for all the devices we tested was about 132 ms, and you’re not likely to notice that 7 ms difference). This isn’t a problem if you’re only listening to audio, but the lag is noticeable if you’re watching video. When we used the aptX Low Latency codec, the latency measured a much more acceptable 29 ms, just under the 31.4 ms average. At that rate, there won’t be a noticeable lip-sync lag. In terms of both frequency response and gain, the ML300 matched the rest of the contenders, as well.
You may read the ML300’s results as “it does what it says.” That’s correct, but it’s also more than what similar models can offer. For example, the TaoTronics TT-BA08 is also supposed to pair to two devices, but we simply couldn’t get that to happen, no matter how many times we followed the instructions in the manual to the letter. This category is a race to the bottom in terms of both price and features, and while the ML300 didn’t absolutely “wow” us, at least it delivered on what it says it will.
The ML300 is a 2.1-inch-by-1.5-inch rectangle with rounded edges, and it measures only about half an inch thick. It isn’t the smallest Bluetooth transmitter we tested, but it is slim enough that it should fit in gym shorts or even yoga-pants pockets. And since it weighs only 0.63 ounces, it won’t weigh you down. In addition to the 3.5 mm auxiliary port and the USB-C charging port, the ML300 has a switch to move between transmitter and receiver modes or to turn off the device, a multifunction button for pairing, and a button to switch to aptX HD. The transmitter comes with a 3.5 mm audio cable, a USB-A–to–USB-C charging cable, and a carrying case.
1Mii says the ML300 has a 10-hour battery life (we didn’t independently test this figure). Although that’s long enough for many flights or a week of trips to the gym, it falls short of the 15- and 16-hour figures some pricier models promise. If you need a longer-lasting battery for lengthy flights or any other reason, consider Aluratek’s ABC01F or Twelve South’s AirFly Pro.
The ML300’s controls are not as intuitive as those of our previous favorite, the now-discontinued Mpow BH259A. You’ll likely need to use the instruction manual to get everything set up, especially if you’re pairing to two devices. There’s only one button that serves multiple functions, including power and pairing, so you have to use a Morse-code-like system of clicks and holds to connect your headphones, and the only real indicator of success is a flashing LED light that’s equally ambiguous. It’s not obvious when you have things in pairing mode, nor when you get that second set of headphones connected, unless you’re closely following the manual.
1Mii’s warranty is unclear. The company’s website states that “all quality-related defects on items sold directly by 1Mii or 1Mii’s authorized resellers are covered by an extensive warranty, starting from the date of purchase,” but it doesn’t specify what that “extensive” warranty period actually is, and our emails to the company have gone unanswered. The ML300 is more affordable than similar models, and there’s not much that physically can break, but if you’re concerned about support, consider one of the models in The competition.
The B03 integrates easily into your existing home theater setup and offers the lowest latency of any transmitter we’ve tested.
If you’re looking for a stationary transmitter to use with your TV or another home audio source, we recommend 1Mii’s B03. It has the same features as the ML300, including good audio quality, aptX Low Latency, support for up to two pairs of headphones, and a receiver mode. But it adds features that are tailored to TV use, including an optical digital-audio input and output so you can pass audio through to a soundbar, an AV receiver, or powered speakers. The B03 lacks an internal battery, but that’s not a crucial feature for a device that will remain in your equipment rack.
In our tests the B03 had lower latency when using the aptX Low Latency codec than any transmitter we’ve tested, at what our resident audio expert Brent Butterworth called a “screamingly low” 10 milliseconds. It may not guarantee perfectly lip-synced video, but it’s as close as you’re going to get with one of these devices. When using the SBC codec, we measured latency at 120 ms. That’s still laggy when you’re watching TV, though, and you may be bothered seeing people’s lips on screen being out of sync with the audio. If your wireless headphones lack aptX Low Latency support and you notice AV sync issues, you can try connecting the Bluetooth transmitter directly to your AV source device (if it has a 3.5 mm or optical audio output), which may cut down on some lag created when the signal has to pass through the TV’s audio processor. Or, consider dedicated wireless TV headphones designed specifically for this purpose.
In addition to its 3.5 mm audio input, the B03 has two optical digital-audio ports: one input for connecting to your TV and one output for connecting to a soundbar or other audio-playback device. This setup allows for audio bypass, meaning you don’t have to unplug the B03 when you want to listen to sound from your external speaker; rather, you just toggle a switch. Other competitors offer a similar setup, but what makes this one different is that you can transmit to Bluetooth at the same time the audio plays out loud, instead of having to choose one over the other. You might want to do this if you’d like to keep up with the audio of a game while you move from room to room, for example, or if someone in your family needs a higher volume level through headphones to hear the dialogue in a TV show.
As for audio performance, the B03’s frequency response and gain were on a par with the results from the rest of the units we tested. The B03 is also one of the few models we found that support the aptX HD codec, which offers higher-fidelity audio if you have compatible headphones.
The B03 is physically larger than our portable pick, but it’s not meant to travel along with you, so that’s okay. It has a footprint of just 4.5 by 3 inches, and it’s only about 1.5 inches tall at its highest, so you should be able to hide it in almost any home theater setup or living room. The lack of a battery means the included Micro-USB cable needs to be plugged in at all times, but the USB port on any modern TV should provide enough power. This transmitter also comes with an optical audio cable, a 3.5 mm audio cable, and an RCA adapter.
The B03 doesn’t have built-in Dolby or DTS decoding, so you should change your TV’s sound output to the PCM setting when using it. If you don’t, you won’t be able to stream from services that offer Dolby Digital output, such as Netflix. The PCM setting downmixes the stream to stereo; in our tests, we didn’t notice any quality differences.
Much like the ML300, the B03 lacks any defined warranty, so you’re taking your chances with service if something goes wrong.
Here are our thoughts on the other Bluetooth transmitters we tested.
Aluratek’s ABT05F is the most popular model at Best Buy, but it doesn’t support a receiver mode. The Aluratek BC01F is more expensive than most of the models we tested in this category, with the only benefit being its 15-hour battery life.
Monoprice’s Premium Bluetooth 5 Transmitter and Receiver (38071) is more expensive than our pick, and while it has a longer battery life, it doesn’t have any additional features, and it often goes out of stock. It’s also quite bulky for a portable transmitter.
Mpow’s BH045B simply feels cheap. It feels lighter than its size suggests, and the switch that moves it between modes doesn’t click into place, so you can’t necessarily be sure you’ve toggled it properly.
TaoTronics’s TT-BA08 doesn’t support aptX HD, and we simply couldn’t get it to connect to two devices at once, no matter how many times we tried.
Twelve South’s AirFly Pro is the best-looking portable transmitter we tested, but it’s also the most expensive. Its controls are frustratingly unintuitive; you get only a single button to control everything, so you need to follow the right combination of clicking and holding to set everything up, and you have to decode the color and pattern of the status light to know whether you’ve connected things properly. The AirFly Pro is also the only model we tested with a permanently attached audio cable—if it breaks, you’ll need to replace the whole unit. We do appreciate that it uses USB-C for charging rather than Micro-USB like the rest, and the 16-hour battery life is the best we found.
1Mii’s B03Pro+ looks and functions like our top pick, but it adds a digital-to-analog converter (DAC) while eliminating the ability to hear from both a soundbar and headphones at the same time. The DAC will affect only the device’s performance as a Bluetooth receiver, so it was not a meaningful addition for our purposes, and we think the B03’s features are more useful.
Avantree’s Oasis Plus is our former favorite TV transmitter. We particularly like its easy controls, supplemented by spoken confirmations. But it has a higher latency than the B03, plus it costs more.
The Avantree Orbit is only a transmitter with no receiver mode, but we decided to test it because of its unique LCD display. While we found the screen useful and the frequency response mostly flat, the latency was problematic. We measured 70 milliseconds in aptX Low Latency and 170 ms in SBC, far greater than the 10 ms and 120 ms the 1Mii B03 delivers in the same tests. The Orbit is also much more expensive than the B03.
MEE Audio’s Connect Hub is expensive, yet it doesn’t offer any obvious benefits over the rest of the field.
TaoTronics’s TT-BA014 worked well in our tests, but it can’t transmit audio through a TV or soundbar and over Bluetooth at the same time (there is a bypass toggle).
Nick Guy is a former senior staff writer covering Apple and accessories at Wirecutter. He has been reviewing iPhones, iPads, and related tech since 2011—and stopped counting after he tested his 1,000th case. It’s impossible for him not to mentally catalog any case he sees. He once had the bright idea to build and burn down a room to test fireproof safes.
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