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A new generation of inexpensive mini amplifiers has made it possible to put together a stereo speaker system for about the same price as you’d pay for a good wireless speaker. Whether you’re building a system for your desktop, den, or dorm, we think the Fosi Audio BT20A is the best way to get started in affordable stereo sound. Combined with a good set of bookshelf speakers, the BT20A can deliver sound quality that even audio enthusiasts will respect.
The BT20A can play loud enough to fill a large room, and it includes features such as Bluetooth connectivity and tone controls.
For those who crave affordability but fear compromise, the Fosi Audio BT20A is the ideal mini stereo amplifier, thanks to its combination of power and features. Even though it’s less than 4 inches wide, it was one of the most powerful amps we tested—powerful enough to drive large tower speakers and to play deep bass tones without strain. The BT20A includes Bluetooth support for easy wireless connection to phones and tablets, as well as bass and treble controls that let you fine-tune the sound to your liking. Standard RCA jacks and a Bluetooth/auxiliary input switch allow for simple hookup and operation. The only real downside is that it looks and feels a little cheap.
The A10 produces clean, powerful sound even through large speakers, and its design is irresistible—but it lacks features like Bluetooth and tone controls.
*At the time of publishing, the price was $63.
When it comes to looks, the Loxjie A10 is the most distinctive mini amp we’ve seen, especially the red version (it’s also available in black). In addition, the A10 is one of the best-performing amps we tested: It was not quite as powerful as the Fosi BT20A, but it was still able to drive large, expensive tower speakers to loud levels, and we slightly preferred the quality of its sound. Its only potential downsides are its lack of Bluetooth support and tone controls, as well as its utter inability to escape visitors’ attention.
The flashy yet compact Tone packs a plethora of features for a paltry price.
Measuring less than 3½ inches wide and offering more features than in many high-end integrated amplifiers, all at a surprisingly low price, the Douk Audio Tone is an exceptional bargain. In our tests it didn’t sound as clear at high volume levels as our other picks, but it has enough power for a bedroom or desktop system. The features are the main attraction, as it provides Bluetooth support, RCA and 3.5 mm analog inputs, a USB digital input, a headphone jack, sturdy speaker-cable binding posts, and a cool-looking front LED power meter.
The BT20A can play loud enough to fill a large room, and it includes features such as Bluetooth connectivity and tone controls.
The A10 produces clean, powerful sound even through large speakers, and its design is irresistible—but it lacks features like Bluetooth and tone controls.
*At the time of publishing, the price was $63.
The flashy yet compact Tone packs a plethora of features for a paltry price.
I’ve reviewed audio gear professionally since 1990. I’ve written reviews for magazines and websites including SoundStage, Sound & Vision, Home Theater Review, Lifewire, and Home Theater. I’ve probably conducted more blind tests of audio components than any other journalist, and my home has a dedicated listening room (where we did the tests for this guide) and a fully equipped test bench, as well as equipment I’ve purchased or built specifically for comparison tests like this.
A mini stereo amplifier is designed for someone who wants to build a great-sounding stereo system that takes up very little space and even less cash. Combine one of these amps with a good pair of bookshelf or outdoor speakers—even an old pair of hand-me-downs that has been gathering dust in the attic—and you can create a system that sounds better than most all-in-one wireless speakers but doesn’t necessarily cost more. It might even cost much less.
In the early 2010s, a new generation of extremely inexpensive, super-efficient audio amplifier chips from companies such as Texas Instruments made it possible to design decent stereo amplifiers that sell for as little as $20 and are smaller than a grilled cheese sandwich. The best mini stereo amps have enough power and sound quality to serve as the heart of a big living room stereo system, but most people use these amps to power small systems in an office, bedroom, dorm room, or garage. These amps are also great for powering outdoor speakers—as long as you keep your amplifier indoors, because none of these amps are water resistant.
Some of these models are just amplifiers, with a stereo analog input, a volume control, and stereo speaker outputs. Others add extra features such as Bluetooth support, tone controls, digital audio inputs, and subwoofer outputs. These amps work with any audio source that has an analog line output or a headphone jack, so you could connect a phone, tablet, or computer using a cable, or add an Amazon Echo Dot, an Echo Flex, or an inexpensive Bluetooth receiver (if the amp doesn’t have built-in Bluetooth).
If you want to listen to sources such as AM/FM radio or a record player, you’re better off buying a stereo receiver, since few (if any) mini amps include an AM/FM tuner or a phono input.
The Sony STR-DH190 stereo receiver is a great way to start an affordable traditional stereo system, especially if you’re into vinyl.
Mini stereo amps are marketed under numerous brands, some of which appear to be owned by the same company, and we often see the same model marketed under multiple brands. Many of these amps look similar, and many use the same Texas Instruments amplifier chip.
In a category where new models pop up like mushrooms after a winter rainstorm, and where so many amps appear only to be slight variants of other amps, it’s impossible to do a comprehensive review. So we simply scoured Amazon and Parts Express to find the most promising and interesting models.
The criteria we used to decide which amps to test included the following:
We tested 10 amps: the Douk Audio G5 and Douk Audio Tone, the Facmogu F900 and S800, the Fosi Audio BT20A, the Lepai LP-168HA and LP-2020TI, the Loxjie A10, the S.M.S.L. SA300, and the Topping MX3. Although we took pains to get in all the biggest names in mini amps, this test group represents a highly subjective sample of what we thought might interest readers. If there are other models you’re curious about, drop us a note in the comments.
It’s common to see reviewers wax eloquently about the differences in sound among amplifiers, but as research has shown, most of these differences disappear when the testing is blind. Making this a blind test was challenging because, due to the COVID-19 pandemic, I wasn’t able to recruit additional listeners, thus I had to serve as both the test administrator and the subject. Fortunately, I have a speaker switcher I designed for blind tests, along with a Behringer Ultralink DS2800 distribution amplifier. By labeling the inputs on the switcher and distribution amp only by number, and by jumbling up the wires so that I didn’t know which amp was assigned to which number, I was able to set up tests in which I didn’t know which amp I was hearing until after I had made my judgments and traced the connections.
I used a voltmeter and a 1-kilohertz test tone (video) to get the output of the amplifiers matched to within ±0.1 decibel, a difference too small for the human ear to detect. This is critical to fair testing because if one amplifier is only slightly louder than the others, the listener is likely to prefer it.
I sourced all my test material from a PC laptop with a Focusrite Scarlett 2i2 USB audio interface, which let me access music from Spotify and Qobuz, as well as test tones stored on the computer. For speakers, I alternated between using the ELAC Debut 2.0 B6.2 (one of our picks for the best bookshelf speaker, which typically sells for $350 per pair) and the Revel Performa3 F206 (a tower speaker costing $3,500 per pair). The subtle differences I heard among these amplifiers were audible through both speakers, but the F206’s greater bass capability and power handling let me push the mini amps to—and sometimes even past—their limits.
The Q Acoustics 3020i is our favorite pair of passive bookshelf speakers, while the Edifier S1000MKII is a great choice if you need a powered speaker set.
The outboard power supply appears to be the weakest link in these amplifiers, and some enthusiasts like to experiment by substituting a larger, more powerful supply. We didn’t pursue this path because we figured that most people who buy these amps just want a good music system and aren’t looking to become audiophiles.
During my blind testing, I judged each amp on its sound quality and its output capabilities, including the following characteristics:
After the blind test, I used the amps casually, listening to music and podcasts at various levels. I also experimented with their different features and controls. I asked the following questions:
I concluded by running lab measurements of the amplifiers to confirm (or, as it turned out, deny) their power ratings and other specifications according to Texas Instruments guidelines (PDF). I focused on two measurements. The first was frequency response, which measures how evenly an amplifier reproduces sound throughout the audio spectrum. Amps with poor frequency response can make bass sound weak or might make high-frequency instruments such as cymbals sound dull.
The second was power output versus total harmonic distortion. Harmonic distortion occurs when an amplifier is pushed to put out higher levels of sound than it’s capable of; as a result, music comes out garbled, harsh, and unclear. Power output measurements tell us how much power an amp can put out at a given level of distortion. The more power, the better, especially when you’re dealing with small, inexpensive amplifiers. This measurement also shows the amount of distortion at low listening levels—something that’s almost never a problem with conventional amps but did prove troublesome with a few mini amps in our tests.
As you can see in the chart below, none of these amps came anywhere close to their claimed power output. This isn’t a big surprise because the power supplies included with them are incapable of that amount. But until such time as the Federal Trade Commission decides to take on Big Mini Amp, we’re confident that when used with most speakers, these amps have enough power to drown out conversation, which is as loud as most people would ever want to play their stereos.
The BT20A can play loud enough to fill a large room, and it includes features such as Bluetooth connectivity and tone controls.
The Fosi Audio BT20A makes it possible to set up a good-sounding stereo system for the price of a mid-level Bluetooth speaker. The BT20A is only about one-thirtieth the size of a typical stereo receiver, yet it delivers clear sound even when driving large speakers at volumes loud enough to drive most people out of the room. Its bass and treble controls let you fine-tune the sound to your liking, and its onboard Bluetooth support allows you to connect wirelessly to phones and tablets with no extra hardware or cables required.
The BT20A is one of the two most powerful mini amps we tested (the other being the Topping MX3). Although that didn’t make a difference when I was listening at moderate levels, I could easily hear the difference when I cranked up the volume. When I played the deep bass notes of Lil Baby’s “Sum 2 Prove” (video) and Holly Cole’s version of “Train Song” (video) at a maximum volume of about 100 dB (similar to the level of the rumble you’d hear on the platform when a train pulls into a station), the BT20A was one of only two mini amps (the other being our runner-up, the Loxjie A10) that didn’t distort or shut themselves off. Even when playing loud through the $3,500 Revel tower speakers, the BT20A sounded clear and strong, with little or no audible distortion, clear vocals, and enough bass to get my chair shaking a bit.
The tone controls on the BT20A are a nice plus, especially if you use the amp with cheap speakers that might need some fine-tuning. My measurements showed that the range of these controls is +6/-7 dB for the treble and +10/-16 dB for the bass, which is plenty for you to get the level of the bass just right for your room or to make harsh-sounding recordings sound a little smoother.
Although none of the mini amps came close to their rated power in our measurement tests, the BT20A was one of the two best. It’s rated at 100 watts per channel into a 4-ohm load at 0.04% total harmonic distortion; however, our single-channel measurements at 1 kilohertz into an 8-ohm load showed 6.0 watts at 1% distortion and 10.8 watts at 10% distortion. Into a 4-ohm load, the numbers were 4.4 watts and 18.5 watts, respectively.
Frequency response (how evenly an amplifier reproduces sound throughout the audio spectrum) wasn’t as good (or flat) as we’d like, but because the error occurs at the lowest and highest parts of the audio spectrum, it’s only marginally audible. Into an 8-ohm load with the tone controls centered, the amp measured -2.37 dB at 20 Hz and -1.86 dB at 20 kHz. By turning the controls just slightly, I improved that to -1.45 dB and -1.24 dB, respectively.
Using a Samsung Galaxy S10 phone as the source, I found the Bluetooth range to be about 50 feet through one window. Like almost all mini amps with Bluetooth, the BT20A supports only the standard SBC Bluetooth audio codec, with no aptX or AAC compatibility. But SBC works with all phones, tablets, and computers, and it generally sounds very good.
The analog audio input uses stereo RCA jacks, which can be a little more convenient than the 3.5 mm jack that many mini amps have. A source switch selects between Bluetooth and the audio input, which is nice because it prevents someone else’s phone or tablet from overriding the analog input unintentionally. The amp is available in silver or black.
The BT20A has small speaker-cable binding posts. They work with speaker cables up to 16 gauge, but a better bet is to put banana plugs on the ends of your cables.
Some mini amps have a button that bypasses the tone controls, but the BT20A doesn’t, so you have no way to precisely set it for a completely flat tonal response. As I found in my measurements, even when the controls are centered, they will always have a bit of an effect, although it probably won’t be much.
The quality of the finish on the silver version looks cheap, and the shiny surface of the knobs is easily scratched.
The A10 produces clean, powerful sound even through large speakers, and its design is irresistible—but it lacks features like Bluetooth and tone controls.
*At the time of publishing, the price was $63.
The Loxjie A10 is appealing in the same way as many products designed by Philippe Starck—it’s barely recognizable for what it is, but its radical design actually increases its functionality. The A10 is one of the more powerful mini amps we tested, and it’s the only one of these amps that seemed to sound better than the others (although only by a smidgen). It doesn’t include Bluetooth support or tone controls, but if you just need a basic amplifier, it’s a superb choice.
In two blind tests, each against three different mini amps, the A10 was the only one of these amplifiers I singled out for sounding a little better than its peers. To me, it sounded slightly more robust and vivid than the other amps, regardless of whether I played it loud or soft, and voices sounded a little less lispy and sibilant through the A10. The A10 also maintained its composure when I played deep-bass material at about 100 dB, producing clean, chair-vibrating bass tones from the Revel tower speakers.
The slim, 2¼-inch-wide design of the A10 makes it easier to fit on a desktop or bookshelf. The A10 has the same miniature speaker-cable binding posts as on the Fosi Audio BT20A, but here they’re spaced farther apart, which makes it easier for you to connect the speaker cables and also permits the use of dual banana plugs. The amp uses a pair of RCA jacks for the audio input, and the only controls are a volume knob and a power button on the front. The A10 is available in a red-anodized or black-matte finish.
The A10, like all the other mini amps we tested, couldn’t even approach its rated power—but graded on a curve, it was a standout, besting all of the less-expensive models we tried. It’s not as powerful as the Fosi Audio BT20A, though. It’s rated at 60 watts per channel into a 4-ohm load at 0.08% total harmonic distortion; our single-channel measurements at 1 kilohertz into an 8-ohm load showed 5.1 watts at 1% distortion and 6.7 watts at 10%. Into a 4-ohm load, the numbers were 9.2 watts and 11.8 watts, respectively. Frequency response into an 8-ohm load was the best (that is, flattest) we measured in this test: -0.08 dB at 20 Hz and -0.06 dB at 20 kHz. That means the A10 will stay faithful to the original balance of bass to midrange to treble in the music you’re listening to.
The only downside to the A10 is that it’s just an amplifier, with no helpful tone controls or built-in Bluetooth. We’d love to see a Bluetooth version. Also, it’s the mini amp we’d least want to fall on top of.
The flashy yet compact Tone packs a plethora of features for a paltry price.
The Douk Audio Tone is one of the smallest and least expensive mini amps we tested, but it has the most features of any under-$100 amp we found, and it performs well for its size and cost. Although it didn’t sound quite as clear and powerful as our other picks when pressed to its limits, it did prove more than adequate to drive our large tower speakers to a satisfying (but not extreme) volume. It also includes Bluetooth support, a headphone jack, and extra analog and digital inputs, and its front power meter is an attention-getting touch.
At normal listening volumes—loud enough that a listener can focus on the music, but not so loud that it drives everyone else out of the house—the Tone sounds similar to our other picks, to the point where few listeners would likely note any difference, much less one worth caring about. The only difference worth noting is that voices can sound subtly coarser, as if the singer had just spent a minute in a smoky bar. When I played hip-hop and jazz recordings with deep bass at about 100 dB, the Tone distorted the sound more than our other picks. Unless you have large speakers with big woofers, or want to play your system loud enough to drown out power-tool noise in the garage, it should work fine.
The Tone’s chassis is extremely compact at just 3 7/16 inches wide, so it takes up very little space on a desktop or shelf. The volume control doubles as a push-button input selector; its position on the top of the amp is especially convenient for desktop use. On the rear panel, you’ll find a set of standard RCA analog input jacks, while the front panel adds a 3.5 mm headphone jack and a 3.5 mm analog mini-jack, plus a USB Micro-B digital audio input for use with computers, phones, and tablets. The amp is available in black or blue, and the Amazon product page also shows a silver version, though we couldn’t find that version for sale.
The front LED power meter is a cool touch; it makes the Tone feel more like a “real” audio component. Two meters are on the front, but they show the same signal level at all times, so it’s actually a dual-mono meter rather than a stereo meter. Considering that the meter is there for ornamentation rather than utility, we’ll forgive this.
While the Tone has a lightweight, plastic chassis, it uses sturdy, metal speaker-cable binding posts spaced to accept single or dual banana plugs, with wire holes big enough to accommodate heavy-gauge cables. Not that the amp requires such cables, but if they’re all you have on hand, this is a nice convenience.
The Tone delivered the least output of all our picks, but its measurement results were fine compared with the other models in its price range. It’s rated at 50 watts per channel into a 4-ohm load at unspecified distortion, though that’s with a 24-volt power supply, and the Tone comes with only a 19-volt power supply. Our single-channel measurements at 1 kilohertz into an 8-ohm load showed 3.4 watts at 1% distortion and 4.9 watts at 10%. Into a 4-ohm load, the numbers were 5.0 watts and 8.3 watts, respectively. Frequency response into an 8-ohm load was -0.27 dB at 20 Hz and -0.47 dB at 20 kHz, an error that wouldn’t be noticeable.
Bluetooth range was about 60 feet through one window when we used a Samsung Galaxy S10 phone as the source.
One potential downside to the Tone is its light weight, which may make it more likely to be pulled off a shelf accidentally. Also, the mirrored finish on the front panel is bound to get scratched; ours showed a few minor wounds after just a couple of days of light use.
Douk Audio G5: This amp would have been our budget pick had the Douk Tone not been available. With built-in Bluetooth support and a sturdy, compact, nice-looking chassis, it’s an appealing choice, but the Tone adds a USB digital input, a headphone output, and a cool-looking power meter for the same amount of money.
Facmogu F900 and S800: These are among the smallest mini amps you can buy, each one about the size of a bar of hand soap. Both work fine at moderate levels, but they lack the power to play loud or to drive large speakers dependably. We considered the F900 as a budget pick because its top-mounted volume control and super-compact size make it so convenient for desktop use.
Lepai LP-168HA: This amp looked interesting because it contains a third amplifier to power a passive subwoofer, but in our tests it sounded distorted at loud volumes, and we found too many quality complaints on Amazon.
Lepai LP-2020TI: The original LP-2020 is the mini amp that first captured audio enthusiasts’ attention. The reengineered TI version remains popular, and it can drive most speakers to a reasonable volume—but with its stock power supply, it tends to distort often at loud levels.
Nobsound One Little Bear G5: This amp’s cute name and compact design almost drew us in, but we saw too many complaints on Amazon about the reliability of its Bluetooth connection.
Pyle MiniBlue: This was another amp with too many complaints about Bluetooth-connection reliability for us to consider.
S.M.S.L. SA300: We were intrigued by this little amp because of its clean design, its use of an Infineon amp chip instead of the ubiquitous TI TPA3116 chip, and its many extra features, such as aptX Bluetooth, tone controls, remote control, a coaxial digital input, a subwoofer output, and a front display. In our tests, however, it sounded slightly thin, and both our ears and our measurements indicated that it was noisier and had higher distortion at low levels than our picks.
Topping MX3: The MX3 looks notably different from the S.M.S.L. SA300 but has most of the same features, plus a headphone jack and an optical digital input. It’s beautifully designed and built, resembling a miniature version of a high-end integrated amplifier. However, we saw too many complaints about reliability and power-off thumping on the subwoofer output to make it a pick. Also, in our experience it sometimes shut itself off when playing loud, after which we had to turn the power back on manually; the S.M.S.L. SA300 did this, too, but it muted only momentarily.
Brent Butterworth is a senior staff writer covering audio and musical instruments at Wirecutter. Since 1989, he has served as an editor or writer on audio-focused websites and magazines such as Home Theater, Sound & Vision, SoundStage, and JazzTimes. He regularly gigs on double bass (and occasionally ukulele) with Los Angeles–area jazz groups.
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