Short answer: the KEF Muo gen2 for tonal balance, the Sony ULT Field 1 for durability. The ULT Field 1 is IP67 rated and survives drops and 1m submersion, but it has an upper midrange peak and rolled off treble. The Muo gen2 is the better-balanced pick, with KEF having fixed the rolled off treble and overall balance, though it still lacks deeper bass.
Buy the Sony ULT Field 1. Both are rated the same for sound quality, and it costs $111.99 less than the KEF Muo gen2.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| KEF Muo gen2 | Sony ULT Field 1 | |
|---|---|---|
| Price | $249.99 | $138.00 |
| Ranked | #84 of 151 in Medium Size Portable Bluetooth Speakers | #87 of 151 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 24 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC, aptX Adaptive up to 48 kHz 24 bit | AAC, SBC |
| IP Rating | IP67 | IP67 |
| Party Mode | Yes (Auracast) | Yes (Party Connect up to 100 speakers) |
| Stereo | Yes | No |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Digital Aux Input | Yes (USB-C) | No |
| Weight | 1.6 lbs (740 g) | 1.4 lbs (650 g) |
| Bluetooth Version | 5.4 | 5.3 |
| Drivers | 1x 58x117mm racetrack woofer, 1x 20mm tweeter | 83mm x 42mm woofer, 16mm tweeter + passive radiator |
| Dimensions | 8.5” x 3.2” x 2.3” (216 x 82 x 59 mm) | 8.1” x 3” x 3” (206 x 77 x 76 mm) |
| Frequency Response | 43Hz - 20kHz (Manufacturer specified) | - |
| Amplifier Power | 40W | - |
| Maximum SPL | 90dB (Manufacturer specified) | - |
| Aux Input | No | No |
| EQ | Yes | Yes |
| Power Input | USB-C | USB-C |
| Built-in Microphone | - | Yes |
| Power Bank | - | No |
| Strap | - | Yes (detachable strap) |
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Prices on this page were last checked October 2, 2026 at 10:18 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 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
Sony ULT Field 1: $138.00 Amazon eBay
Older models: the Sony XB23 (ranked higher, rated 3.3/5) and the Sony SRS-XB20 (ranked lower, rated 2.8/5).
Pros: IP67 rated, survives drops and 1m submersion. Real-world battery around 28+ hours with ULT (bass boost) mode off. Stereo-pairs with a second ULT Field 1.
Cons: Upper midrange peak, rolled off treble
Full Sony ULT Field 1 review and specifications →
| App | Yes |
|---|---|
| Aux Input | No |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | AAC, SBC |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 8.1” x 3” x 3” (206 x 77 x 76 mm) |
| Drivers | 83mm x 42mm woofer, 16mm tweeter + passive radiator |
| EQ | Yes |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Party Connect up to 100 speakers) |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | No |
| Strap | Yes (detachable strap) |
| TWS | Yes |
| Weight | 1.4 lbs (650 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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