These are not really the same size class, and that is the honest framing here. The Marshall Kilburn III ranks #41 of 97 large speakers by sound quality at $379.99; the Marshall Bromley 450 ranks #24 of 44 party speakers by sound quality at $649.95.
The Marshall Kilburn III is the lighter choice. Spacious soundstage with broad stereo dispersion from Marshall’s True Stereophonic multi-driver layout, delivering warm, room-filling sound with 45Hz bass extension. At 6.3 lbs (2.85 kg) it weighs much less than the Marshall Bromley 450 at 27.1 lbs (12.3 kg). Watch for: 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.
The case for the Marshall Bromley 450: A balanced, warm sound with a flat midrange that keeps vocals and instruments clear, plenty of bass rumble and enough treble for energetic vocals, per RTINGS’ lab tests. The tradeoff: It is the quietest of its rivals: both the Soundboks Mix and Teufel Rockster Air 2 play louder, and near max volume the bass recedes and the sound gets less composed.
Buy the Marshall Kilburn III at $379.99 if you want a large speaker. Buy the Marshall Bromley 450 at $649.95 if you want a party speaker instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| Marshall Kilburn III | Marshall Bromley 450 | |
|---|---|---|
| Price | $379.99 | $649.95 |
| Ranked | #41 of 97 in Large Size Portable Bluetooth Speakers | #24 of 44 in Party Size Portable Bluetooth Speakers |
| Amplifier Power | 50W | 400W |
| App | Yes | Yes (Marshall Bluetooth app) |
| Aux Input | Yes | Yes (3.5mm, RCA) |
| Bass Extension (-10dB) | 45Hz | - |
| Battery Life | 50 hours (Manufacturer specified) | 40+ hours (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC, AAC | SBC, AAC, LC3 |
| Bluetooth Version | 5.3 | 5.3 |
| Built-in Microphone | No | No |
| Digital Aux Input | No | Yes (USB-C) |
| Dimensions | 10.7” x 5.9” x 6.7” (272 x 150 x 170 mm) | 14.4” x 19.4” x 10.3” (366 x 492 x 261 mm) |
| Drivers | 1x 4” woofer + 2x 2” full-range drivers | 2x 6.5” woofers, 4x 2” full-range drivers, 2 passive radiators |
| EQ | Yes | Yes |
| Frequency Response | 45Hz - 20kHz | 42Hz - 20kHz (Manufacturer specified) |
| IP Rating | IP54 | IP55 |
| Maximum SPL | 91dB | - |
| Omnidirectional | No | Yes |
| Party Mode | Yes (Auracast) | Yes (Auracast) |
| Power Bank | Yes | Yes (USB-C) |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Yes |
| Strap | Yes (built-in strap) | No |
| TWS | Yes | No |
| Weight | 6.3 lbs (2.85 kg) | 27.1 lbs (12.3 kg) |
| Charging Time | - | 3.5 hours |
| Removable Battery | - | Yes |
| Microphone Input | - | Yes (2x XLR/6.35mm combo) |
| XLR Input | - | Yes (2x combo) |
| Guitar Input | - | Yes |
| USB Playback | - | No |
| Wi-Fi | - | No |
| Lights | - | Yes |
| Wheels | - | No |
Related Speaker Comparisons
How Marshall Kilburn III compares with other leading options:
- JBL Xtreme 5 vs Marshall Kilburn III
- Tribit Stormbox Lava vs Marshall Kilburn III
- Brane X vs Marshall Kilburn III
- Soundcore Boom 2 vs Marshall Kilburn III
- Marshall Stockwell II vs Marshall Kilburn III
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
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
- Marshall Kilburn III vs Marshall Kilburn II
- Marshall Kilburn III vs JBL Xtreme 4
- Marshall Kilburn III vs Ultimate Ears Everboom
- Marshall Kilburn III vs W-King T9
- Marshall Kilburn III vs Marshall Middleton
- Marshall Kilburn III vs Devialet Mania
- Marshall Kilburn III vs Marshall Middleton II
- Marshall Kilburn III vs Sony ULT Field 5
- See all 31 comparisons
Marshall Bromley 450: $649.95 Amazon B&H Photo Video eBay
Pros: A balanced, warm sound with a flat midrange that keeps vocals and instruments clear, plenty of bass rumble and enough treble for energetic vocals, per RTINGS’ lab tests. Drivers on all four sides keep the tonal balance nearly the same from any angle, and M1M Tech Channel found it more open and airy than the Soundboks Mix and Teufel Rockster Air 2, with deeper bass than both. RTINGS measured 18.8 hours of battery from a swappable LiFePO4 pack shared with the Bromley 750, and it adds IP55 protection, two XLR/6.35mm combo inputs, USB-C audio, Auracast and physical bass and treble knobs.
Cons: It is the quietest of its rivals: both the Soundboks Mix and Teufel Rockster Air 2 play louder, and near max volume the bass recedes and the sound gets less composed. The warm tuning lacks some fine treble detail. There is no graphic EQ, only bass and treble knobs, and its stereo spreads left and right channels around the cabinet, so panned elements can land on the wrong side. At 12.3 kg it has a carry handle but no wheels.
Full Marshall Bromley 450 review and specifications →
| Amplifier Power | 400W |
|---|---|
| App | Yes (Marshall Bluetooth app) |
| Aux Input | Yes (3.5mm, RCA) |
| Battery Life | 40+ hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC, AAC, LC3 |
| Bluetooth Version | 5.3 |
| Built-in Microphone | No |
| Charging Time | 3.5 hours |
| Digital Aux Input | Yes (USB-C) |
| Dimensions | 14.4” x 19.4” x 10.3” (366 x 492 x 261 mm) |
| Drivers | 2x 6.5” woofers, 4x 2” full-range drivers, 2 passive radiators |
| EQ | Yes |
| Frequency Response | 42Hz - 20kHz (Manufacturer specified) |
| Guitar Input | Yes |
| IP Rating | IP55 |
| Lights | Yes |
| Microphone Input | Yes (2x XLR/6.35mm combo) |
| Omnidirectional | Yes |
| Party Mode | Yes (Auracast) |
| Power Bank | Yes (USB-C) |
| Power Input | USB-C |
| Removable Battery | Yes |
| Stereo | Yes |
| Strap | No |
| TWS | No |
| USB Playback | No |
| Weight | 27.1 lbs (12.3 kg) |
| Wheels | No |
| Wi-Fi | No |
| XLR Input | Yes (2x combo) |
- Links
- Reviews, Comparisons and Sound Samples
- RTINGS: Marshall Bromley 450 Review More from Rtings.com →
- M1M Tech Channel: The best in its class? Marshall Bromley 450 vs. Soundboks & Teufel More from M1MTechChannel →
- HeadphoneCheck: Marshall Bromley 450 test
- Tom’s Guide: Marshall Bromley 450 vs Bromley 750 face-off
- Smart Home Sounds: Marshall Bromley 450 review More from Smart Home Sounds →
- Storytripper HD: JBL Partybox 120 vs Marshall Bromley 450 (Indoor) More from storytripperhd →
- Storytripper HD: Marshall Bromley 450 vs Marshall Bromley 750 (outdoor)
- Storytripper HD: Marshall Woburn III vs Marshall Bromley 450
- Head-to-Head Comparisons
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- See all 20 comparisons