Short answer: the KEF Muo gen2 for better sound quality, the Ultimate Ears Boom 4 for the lower price. The KEF Muo gen2 ranks #97 of 175 medium speakers, rated 3.1/5, at $249.99. The Ultimate Ears Boom 4 ranks #113, rated 2.9/5, at $129.99, $120 cheaper.
The KEF Muo gen2 is the longer-running option. KEF seemed to have fixed the rolled off treble and overall balance. It is rated for 24 hours of battery against 15 for the Ultimate Ears Boom 4. It supports aptX Adaptive Bluetooth, which the Ultimate Ears Boom 4 lacks. The tradeoff: Lacking deeper bass.
Why pick the Ultimate Ears Boom 4: IP67 rated, floats, and finally charges via USB-C instead of the older Booms’ Micro-USB. The tradeoff: Not much improvement over the old ones.
Buy the KEF Muo gen2 when sound quality outweighs the price for you, and the Ultimate Ears Boom 4 when the price outweighs sound quality instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| KEF Muo gen2 | Ultimate Ears Boom 4 | |
|---|---|---|
| Price | $249.99 | $129.99 |
| Ranked | #97 of 175 in Medium Size Portable Bluetooth Speakers | #113 of 175 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 24 hours (Manufacturer specified) | 15 hours (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC, aptX Adaptive up to 48 kHz 24 bit | SBC |
| IP Rating | IP67 | IP67 |
| Party Mode | Yes (Auracast) | - |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Digital Aux Input | Yes (USB-C) | No |
| Weight | 1.6 lbs (740 g) | 1.4 lbs (620 g) |
| Bluetooth Version | 5.4 | 5.1 |
| Drivers | 1x 58x117mm racetrack woofer, 1x 20mm tweeter | 2x 1.57” (40mm) active drivers + 2x 1.81” x 2.57” (46.1 x 65.2mm) passive radiators |
| Dimensions | 8.5” x 3.2” x 2.3” (216 x 82 x 59 mm) | 7.2” x 2.9” x 2.9” (184 x 73 x 73 mm) |
| Frequency Response | 43Hz - 20kHz (Manufacturer specified) | - |
| Amplifier Power | 40W | - |
| Maximum SPL | 90dB (Manufacturer specified) | 85dBC (Manufacturer specified) |
| Aux Input | No | No |
| EQ | Yes | Yes (via app) |
| Power Input | USB-C | USB-C |
| Built-in Microphone | - | No |
| Power Bank | - | No |
| Strap | - | Yes (built-in loop) |
Related Speaker Comparisons
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- Soundcore Boost “upgraded” 2021 vs KEF Muo gen2
- Denon Envaya DSB-250BT vs KEF Muo gen2
Prices on this page were last checked October 12, 2026 at 4:13 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
KEF Muo gen2: $249.99 Amazon $249.99 eBay
Pros: KEF seemed to have fixed the rolled off treble and overall balance
Cons: Lacking deeper bass. Very thuddy bass. Appears to be the exact same hardware but with updated tuning. Bass distorts as volume increases, and the claimed 43Hz extension is really only audible at low listening volumes, with a few seconds of lag after volume changes. Loses most of its bass off-axis. Customer reviews are mixed, ranging from praise for detail at low volume to complaints of a boxy, hollow sound.
Full KEF Muo gen2 review and specifications →
| Amplifier Power | 40W |
|---|---|
| App | Yes |
| Aux Input | No |
| Battery Life | 24 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC, aptX Adaptive up to 48 kHz 24 bit |
| Bluetooth Version | 5.4 |
| Digital Aux Input | Yes (USB-C) |
| Dimensions | 8.5” x 3.2” x 2.3” (216 x 82 x 59 mm) |
| Drivers | 1x 58x117mm racetrack woofer, 1x 20mm tweeter |
| EQ | Yes |
| Frequency Response | 43Hz - 20kHz (Manufacturer specified) |
| IP Rating | IP67 |
| Maximum SPL | 90dB (Manufacturer specified) |
| Omnidirectional | No |
| Party Mode | Yes (Auracast) |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| Weight | 1.6 lbs (740 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Ultimate Ears Boom 4: $129.99 Amazon $129.99 eBay
Older model: the Ultimate Ears Boom 3 (ranked lower, rated 2.9/5). See every Ultimate Ears Wonderboom, Boom and Megaboom generation.
Same family: the Ultimate Ears Wonderboom 4 (smaller model, ranked higher, rated 2.9/5) and the Ultimate Ears Megaboom 4 (larger model, ranked lower, rated 2.1/5).
Pros: IP67 rated, floats, and finally charges via USB-C instead of the older Booms’ Micro-USB. 15 hour battery. Customizable EQ and speaker-pairing via the UE app.
Cons: Not much improvement over the old ones. Weak bass extension and thuddy bass. Gets distorted above 90%
Full Ultimate Ears Boom 4 review and specifications →
| Released | Jun 2024 (2 years ago) |
|---|---|
| App | Yes |
| Aux Input | No |
| Battery Life | 15 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.1 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 7.2” x 2.9” x 2.9” (184 x 73 x 73 mm) |
| Drivers | 2x 1.57” (40mm) active drivers + 2x 1.81” x 2.57” (46.1 x 65.2mm) passive radiators |
| EQ | Yes (via app) |
| IP Rating | IP67 |
| Maximum SPL | 85dBC (Manufacturer specified) |
| Omnidirectional | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (built-in loop) |
| TWS | Yes |
| Weight | 1.4 lbs (620 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Ultimate Ears Boom 4 vs Ultimate Ears Boom 3
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom
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- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom 2
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom 3
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom 4
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