Short answer: the JBL Xtreme 4. Both are rated 3.8/5 for sound quality (#43 and #41 of 97 large speakers), and the JBL Xtreme 4 costs $309.95 against $379.99 for the Marshall Kilburn III, so with nothing between them on sound quality, price settles it.
The JBL Xtreme 4 is the lighter, tougher pick. A rugged 4.6 lbs (2.1 kg) portable with IP67 protection, a replaceable battery, USB-C power-bank output, Auracast, stereo pairing and a useful 5-band app EQ. 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 IP67 against IP54 for the Marshall Kilburn III. The catch: It cannot produce the deep rumble of a larger speaker, and bass compression increases near maximum volume.
The Marshall Kilburn III is the longer-running option. 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 24 for the JBL Xtreme 4. It supports AAC Bluetooth, which the JBL Xtreme 4 lacks. It keeps a wired aux input, which the JBL Xtreme 4 lacks. 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 JBL Xtreme 4. Both are rated the same for sound quality, and it costs $70.04 less than the Marshall Kilburn III.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| JBL Xtreme 4 | Marshall Kilburn III | |
|---|---|---|
| Price | $309.95 | $379.99 |
| Ranked | #43 of 97 in Large Size Portable Bluetooth Speakers | #41 of 97 in Large Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Aux Input | No | Yes |
| Battery Life | 24 hours (Manufacturer specified) | 50 hours (Manufacturer specified) |
| EQ | Yes (5 band) | Yes |
| IP Rating | IP67 | IP54 |
| Bluetooth Latency | 220ms | - |
| Maximum SPL | 106dB (measured by Alan Ross Reviews) | 91dB |
| Party Mode | Yes (Auracast) | Yes (Auracast) |
| Power Bank | Yes (USB-C) | Yes |
| Power Input | USB-C | USB-C |
| Removable Battery | Yes | - |
| TWS | Yes | Yes |
| Weight | 4.6 lbs (2.1 kg) | 6.3 lbs (2.85 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC, AAC |
| Built-in Microphone | Yes | No |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 11.7” x 5.9” x 5.6” (297 x 149 x 141 mm) | 10.7” x 5.9” x 6.7” (272 x 150 x 170 mm) |
| Drivers | 2x 70mm woofers, 2x 19mm tweeters + 2x passive radiators | 1x 4” woofer + 2x 2” full-range drivers |
| Frequency Response | 44Hz - 20kHz (Manufacturer specified) | 45Hz - 20kHz |
| Amplifier Power | 100W | 50W |
| Digital Aux Input | No | No |
| Strap | Yes (detachable shoulder strap) | Yes (built-in strap) |
| Bass Extension (-10dB) | - | 45Hz |
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More worthwhile head-to-heads for Marshall Kilburn III:
- 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
JBL Xtreme 4: $309.95 Amazon B&H Photo Video eBay
Newer model: the JBL Xtreme 5, ranked higher, rated 4.6/5.
Pros: A rugged 2.1kg portable with IP67 protection, a replaceable battery, USB-C power-bank output, Auracast, stereo pairing and a useful 5-band app EQ. Independent reviews find the midrange detailed and the sound clear, punchy and refined for outdoor use; it also reaches a strong 106dB maximum level and has excellent real-world battery life.
Cons: It cannot produce the deep rumble of a larger speaker, and bass compression increases near maximum volume. The front-facing layout has only modest off-axis consistency, Bluetooth latency is high for video, and the default balance benefits from EQ adjustment. There is no aux input, so wired sources are not supported. Out of the box it leans bass-boosted, with a dip between the upper bass and midrange that EQ cannot fix, and it pushes the upper mids and treble at high volume. It is also expensive.
Full JBL Xtreme 4 review and specifications →
| Amplifier Power | 100W |
|---|---|
| App | Yes |
| Aux Input | No |
| Battery Life | 24 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Latency | 220ms |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 11.7” x 5.9” x 5.6” (297 x 149 x 141 mm) |
| Drivers | 2x 70mm woofers, 2x 19mm tweeters + 2x passive radiators |
| EQ | Yes (5 band) |
| Frequency Response | 44Hz - 20kHz (Manufacturer specified) |
| IP Rating | IP67 |
| Maximum SPL | 106dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | Yes (Auracast) |
| Power Bank | Yes (USB-C) |
| Power Input | USB-C |
| Removable Battery | Yes |
| Stereo | Yes |
| Strap | Yes (detachable shoulder strap) |
| TWS | Yes |
| Weight | 4.6 lbs (2.1 kg) |
- Links
- Reviews, Comparisons and Sound Samples
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- JOY‘s 🎧3D🔈Audio-Show: JBL Charge 6 vs JBL Xtreme 4 - outdoor test
- JOY‘s 🎧3D🔈Audio-Show: JBL Charge 6 vs JBL Xtreme 4 - basstest (bigger=better?)
- Alan Ross Reviews: JBL Xtreme 4 vs Flip 7 vs Charge 6 – The ULTIMATE JBL Speaker Showdown! More from alanrossreviews →
- Oluv Patreon: SoundCore Boom 3i - first impressions & EQs
- Mateusz Cholewa: TRIBIT StormBox LAVA Deep BASS 🆚 JBL XTREME 4 More from Mateusz Cholewa →
- Mateusz Cholewa: Marshall Middleton👌🎶 🆚 JBL Xtreme 4 🎶📢
- Oluv Patreon: JBL Xtreme 4 - sound analysis
- Oluv Patreon: JBL Xtreme 4 - unboxing & first impressions
- Oluv Patreon: Harman Kardon go+play 3 vs JBL Xtreme 4 - first impressions
- Dominik Reviews: JBL Xtreme 4 vs JBL Xtreme 3 Sound Test 😍 Best upgrade in the history? 😂 More from Dominik Reviews →
- M1MTechChannel: Welche JBL Partybox ist die BESTE ? Alle Partyboxen im Vergleich | 2026 More from M1MTechChannel →
- Mateusz Cholewa: BOGASING S8 Pro Max 100W vs JBL Xtreme 4 Audio Test
- Mateusz Cholewa: LOEWE We HEAR Pro Super Stereo vs JBL Xtreme 4
- Head-to-Head Comparisons
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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