Short answer: the Soundcore Motion X500. It ranks #27 of 97 large speakers by sound quality, rated 4.1/5, at $99.99; the Marshall Kilburn III ranks #41, rated 3.8/5, and costs $379.99, so there is little reason to consider the other one.
The Soundcore Motion X500 is the lighter, tougher pick. 40W stereo with 3-driver layout (two tweeters + woofer). At 4.6 lbs (2.1 kg) it weighs noticeably less than the Marshall Kilburn III at 6.3 lbs (2.85 kg). It is rated IPX7 against IP54 for the Marshall Kilburn III. It supports LDAC Bluetooth, which the Marshall Kilburn III lacks. The catch: A little bright on top, a custom EQ can flatten things out a bit.
The Marshall Kilburn III is the longer-running choice. Spacious soundstage with broad stereo dispersion from Marshall’s True Stereophonic multi-driver layout, delivering warm, room-filling sound with 45Hz bass extension. It is rated for 50 hours of battery against 12 for the Soundcore Motion X500. It links with other speakers (Auracast), which the Soundcore Motion X500 cannot. The tradeoff: Noticeable dips in the midrange compromise frequency response neutrality, making vocals and acoustic instruments sound somewhat recessed or muffled compared to more linear competitors like the JBL Xtreme 4 unless the bass dial is dialed back.
Buy the Soundcore Motion X500. It is rated higher for sound quality than the Marshall Kilburn III and costs less, so only choose the other one for a particular feature it does better.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Specifications Side By Side
| Soundcore Motion X500 | Marshall Kilburn III | |
|---|---|---|
| Price | $99.99 | $379.99 |
| Ranked | #27 of 97 in Large Size Portable Bluetooth Speakers | #41 of 97 in Large Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Bass Extension (-10dB) | 48Hz | 45Hz |
| Battery Life | 12 hours (Manufacturer specified) | 50 hours (Manufacturer specified) |
| EQ | Yes | Yes |
| IP Rating | IPX7 | IP54 |
| Maximum SPL | 104dB (measured by Alan Ross Reviews) | 91dB |
| Party Mode | No | Yes (Auracast) |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 4.6 lbs (2.1 kg) | 6.3 lbs (2.85 kg) |
| Aux Input | Yes | Yes |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | LDAC, SBC | SBC, AAC |
| Built-in Microphone | Yes | No |
| Power Bank | No | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 8.7” x 8” x 3.2” (220 x 202 x 81 mm) | 10.7” x 5.9” x 6.7” (272 x 150 x 170 mm) |
| Drivers | 2x 58mm (2.3”) forward-firing full-range drivers + 1x 43mm (1.7”) upward-firing driver | 1x 4” woofer + 2x 2” full-range drivers |
| Frequency Response | 50Hz - 40kHz (Manufacturer specified) | 45Hz - 20kHz |
| Amplifier Power | 40W | 50W |
| Digital Aux Input | No | No |
| Strap | No | Yes (built-in 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
Soundcore Motion X500: $99.99 Amazon eBay
Pros: 40W stereo with 3-driver layout (two tweeters + woofer). IPX7 weatherproof rating. Compact and very portable. Fine build quality at this price. Spatial Dynamic mode provides immersive sound. Gets close to 12 hour battery claim. Measured bass extension of 48Hz (-10dB).
Cons: A little bright on top, a custom EQ can flatten things out a bit. Peaks at 250Hz and dip at 1kHz
Full Soundcore Motion X500 review and specifications →
| Amplifier Power | 40W |
|---|---|
| App | Yes |
| Aux Input | Yes |
| Bass Extension (-10dB) | 48Hz |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | LDAC, SBC |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 8.7” x 8” x 3.2” (220 x 202 x 81 mm) |
| Drivers | 2x 58mm (2.3”) forward-firing full-range drivers + 1x 43mm (1.7”) upward-firing driver |
| EQ | Yes |
| Frequency Response | 50Hz - 40kHz (Manufacturer specified) |
| IP Rating | IPX7 |
| Maximum SPL | 104dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | No |
| TWS | Yes |
| Weight | 4.6 lbs (2.1 kg) |
- Links
- Reviews, Comparisons and Sound Samples
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Marshall Kilburn III: $379.99 Amazon eBay
Older model: the Marshall Kilburn II (ranked lower, rated 3.8/5).
Pros: Spacious soundstage with broad stereo dispersion from Marshall’s True Stereophonic multi-driver layout, delivering warm, room-filling sound with 45Hz bass extension. Independent physical bass and treble dials allow quick tonal adjustments on the fly, backed by app-based EQ and placement compensation. Battery life is outstanding at up to 50+ hours with USB-C power-bank charging, IP54 splash resistance, 3.5mm aux input, and Bluetooth 5.3 with Auracast broadcast support. Measured bass extension of 45Hz (-10dB).
Cons: Noticeable dips in the midrange compromise frequency response neutrality, making vocals and acoustic instruments sound somewhat recessed or muffled compared to more linear competitors like the JBL Xtreme 4 unless the bass dial is dialed back. Kilburn II retains slightly punchier perceived loudness at maximum volume due to a more aggressive V-shaped contour. At 2.85 kg with only IP54 splash resistance, it is heavy and cannot withstand water immersion. Lacks a built-in microphone and LDAC codec support.
Full Marshall Kilburn III review and specifications →
| Amplifier Power | 50W |
|---|---|
| App | Yes |
| Aux Input | Yes |
| Bass Extension (-10dB) | 45Hz |
| Battery Life | 50 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC, AAC |
| Bluetooth Version | 5.3 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 10.7” x 5.9” x 6.7” (272 x 150 x 170 mm) |
| Drivers | 1x 4” woofer + 2x 2” full-range drivers |
| EQ | Yes |
| Frequency Response | 45Hz - 20kHz |
| IP Rating | IP54 |
| Maximum SPL | 91dB |
| Omnidirectional | No |
| Party Mode | Yes (Auracast) |
| Power Bank | Yes |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (built-in strap) |
| TWS | Yes |
| Weight | 6.3 lbs (2.85 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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