Short answer: the Marshall Kilburn III for better sound quality, the Zealot S97 for the lower price. The Marshall Kilburn III ranks #41 of 97 large speakers, rated 3.8/5, at $379.99. The Zealot S97 ranks #58, rated 3.4/5, at $78.62, $301.37 cheaper.
The Marshall Kilburn III is the better-sounding, 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 12 for the Zealot S97. It supports AAC Bluetooth, which the Zealot S97 lacks. 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 Zealot S97 is the tougher option. For a compact 7.3 lbs (3.3 kg) boombox, the S97 delivers unusually deep, clean-enough bass with a more sensible default balance than many inexpensive Zealot models. It is rated IPX6 against IP54 for the Marshall Kilburn III. The tradeoff: It is not especially loud for its size, battery life is only a claimed 12 hours, and the bass preset can swamp the rest of the music.
Buy the Marshall Kilburn III when sound quality outweighs the price for you, and the Zealot S97 when the price outweighs sound quality instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| Marshall Kilburn III | Zealot S97 | |
|---|---|---|
| Price | $379.99 | $78.62 |
| Ranked | #41 of 97 in Large Size Portable Bluetooth Speakers | #58 of 97 in Large Size Portable Bluetooth Speakers |
| Amplifier Power | 50W | 80W |
| App | Yes | No |
| Aux Input | Yes | Yes |
| Bass Extension (-10dB) | 45Hz | - |
| Battery Life | 50 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC, AAC | SBC |
| Bluetooth Version | 5.3 | 5.2 |
| Built-in Microphone | No | Yes |
| Digital Aux Input | No | No |
| Dimensions | 10.7” x 5.9” x 6.7” (272 x 150 x 170 mm) | 12.6” x 7.3” x 5.9” (321 x 185 x 151 mm) |
| Drivers | 1x 4” woofer + 2x 2” full-range drivers | 2x 76mm (3”) woofers + 2x 38mm tweeters + 2x passive radiators |
| EQ | Yes | 3 EQ presets |
| Frequency Response | 45Hz - 20kHz | - |
| IP Rating | IP54 | IPX6 |
| Maximum SPL | 91dB | - |
| Omnidirectional | No | No |
| Party Mode | Yes (Auracast) | Yes (PartyAdd up to 100 speakers) |
| Power Bank | Yes | Yes (USB-A + USB-C) |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Yes |
| Strap | Yes (built-in strap) | - |
| TWS | Yes | No |
| Weight | 6.3 lbs (2.85 kg) | 7.3 lbs (3.3 kg) |
| MicroSD Playback | - | Yes |
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
Zealot S97: $78.62 Amazon eBay
Pros: For a compact 3.3kg boombox, the S97 delivers unusually deep, clean-enough bass with a more sensible default balance than many inexpensive Zealot models. It also brings IPX6 protection, aux and microSD playback, power-bank outputs, three EQ presets and PartyAdd linking.
Cons: It is not especially loud for its size, battery life is only a claimed 12 hours, and the bass preset can swamp the rest of the music. There is no app or fine-grained EQ, so the Vocal preset is the only practical way to improve the balance. It is still heavy for a speaker with this output ceiling.
Full Zealot S97 review and specifications →
| Amplifier Power | 80W |
|---|---|
| App | No |
| Aux Input | Yes |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 12.6” x 7.3” x 5.9” (321 x 185 x 151 mm) |
| Drivers | 2x 76mm (3”) woofers + 2x 38mm tweeters + 2x passive radiators |
| EQ | 3 EQ presets |
| IP Rating | IPX6 |
| MicroSD Playback | Yes |
| Omnidirectional | No |
| Party Mode | Yes (PartyAdd up to 100 speakers) |
| Power Bank | Yes (USB-A + USB-C) |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | No |
| Weight | 7.3 lbs (3.3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons