Short answer: the Brane X on measured sound quality, the Marshall Kilburn II on price. The Brane X ranks #4 of 78 large speakers at $500. The Marshall Kilburn II ranks #36 at $219, $281 cheaper.
What the Marshall Kilburn II offers: 20W Class D amp + dual 8W tweeters. 20+ hour battery with quick-charge (20 min charges 3 hours of play). Rugged design with leather handle and reinforced corners, IPX2 rated. Thrives with rock music. Bluetooth 5.0 with 30ft range. Watch for: Boosted upper bass, not very detailed, not as deep bass as competitors, upper mids peak. Very low IPX2 water rating. AC charging
What the Brane X offers: The Brane X pairs a dedicated RAD subwoofer with two midrange drivers and two tweeters to achieve extraordinary low bass for a 3.5kg portable: its measured -10dB extension is 31Hz. Independent testing finds it loud, with well-balanced mids, a smooth treble balance and useful bass-level controls; Wi-Fi, AirPlay, Alexa, quality Bluetooth codecs and low-latency aux pass-through make it unusually versatile. Watch for: The front-facing design has only moderate dispersion, so sound changes noticeably off to the sides or behind it. Bass response shifts at maximum volume, the default aux mode has very high latency, and some listeners find the upper register edgy or need EQ to achieve their preferred balance. Its claimed 12-hour runtime and premium cost make it more of a compact high-end system than a carefree all-day speaker.
Buy the Marshall Kilburn II when the price outweighs sound quality for you, and the Brane X when sound quality outweighs the price instead.
If battery life is a priority, the Marshall Kilburn II is rated for 20 hours versus 12 hours for the Brane X.
There is a real gap in water resistance: the Brane X at IP57 (brief submersion) against the Marshall Kilburn II, which has IPX2 (light drips).
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Marshall Kilburn II | Brane X | |
|---|---|---|
| Price | $219.00 | $500 |
| Ranked | #36 of 78 in Large Size Portable Bluetooth Speakers | #4 of 78 in Large Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Bass Extension (-10dB) | ~58Hz | 31Hz |
| Battery Life | 20 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| IP Rating | IPX2 | IP57 |
| Weight | 5.5 lbs (2.49 kg) | 7.7 lbs (3.5 kg) |
| App | No | No |
| Bluetooth Codecs | SBC | aptX HD, aptX, AAC, SBC |
| Built-in Microphone | Yes | Yes |
| EQ | No | No |
| Party Mode | No | Yes (Brane app, up to 8 speakers) |
| Power Bank | No | No |
| Power Input | USB-C | AC Power brick |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Amplifier Power | 36W | 200W |
| Dimensions | 9.6" x 6.4" x 5.5" (243 x 162 x 140 mm) | 9.3" x 7" x 6.1" (236 x 178 x 155 mm) |
| Drivers | 1x 4" (102mm) woofer + 2x 20mm dome tweeters | 2x 2.5" midrange, 2x 0.75" tweeters + 6.5"x9" subwoofer |
| Maximum SPL | 102dB (Manufacturer specified) | 106dB (measured by Alan Ross Reviews) |
| Digital Aux Input | No | No |
| Aux Latency | - | 295ms default, 33ms with aux pass-through |
| Bluetooth Latency | - | 100ms |
| Wi-Fi | - | Yes |
| Frequency Response | - | 30Hz - 20kHz (Manufacturer specified) |
Related Speaker Comparisons
How Brane X compares with other leading options:
- Brane X vs Vifa Helsinki
- Brane X vs JBL Xtreme 5
- Brane X vs Tribit Stormbox Lava
- Brane X vs Minirig 4 with subwoofer
- Brane X vs Minirig 3 with subwoofer
Prices on this page were last checked September 16, 2026 at 12:41 AM 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 II: $219.00 Amazon eBay
Pros: 20W Class D amp + dual 8W tweeters. 20+ hour battery with quick-charge (20 min charges 3 hours of play). Rugged design with leather handle and reinforced corners, IPX2 rated. Thrives with rock music. Bluetooth 5.0 with 30ft range. Measured bass extension of ~58Hz (-10dB).
Cons: Boosted upper bass, not very detailed, not as deep bass as competitors, upper mids peak. Very low IPX2 water rating. AC charging
Full Marshall Kilburn II review and specifications →
| Amplifier Power | 36W |
|---|---|
| App | No |
| Aux Input | Yes |
| Bass Extension (-10dB) | ~58Hz |
| Battery Life | 20 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 9.6" x 6.4" x 5.5" (243 x 162 x 140 mm) |
| Drivers | 1x 4" (102mm) woofer + 2x 20mm dome tweeters |
| EQ | No |
| IP Rating | IPX2 |
| Maximum SPL | 102dB (Manufacturer specified) |
| Omnidirectional | No |
| Party Mode | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| Weight | 5.5 lbs (2.49 kg) |
- Reviews, Comparisons and Sound Samples
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Brane X: $500 Amazon eBay
Pros: The Brane X pairs a dedicated RAD subwoofer with two midrange drivers and two tweeters to achieve extraordinary low bass for a 3.5kg portable: its measured -10dB extension is 31Hz. Independent testing finds it loud, with well-balanced mids, a smooth treble balance and useful bass-level controls; Wi-Fi, AirPlay, Alexa, quality Bluetooth codecs and low-latency aux pass-through make it unusually versatile. Measured bass extension of 31Hz (-10dB).
Cons: The front-facing design has only moderate dispersion, so sound changes noticeably off to the sides or behind it. Bass response shifts at maximum volume, the default aux mode has very high latency, and some listeners find the upper register edgy or need EQ to achieve their preferred balance. Its claimed 12-hour runtime and premium cost make it more of a compact high-end system than a carefree all-day speaker.
Full Brane X review and specifications →
| Amplifier Power | 200W |
|---|---|
| App | No |
| Aux Input | Yes |
| Aux Latency | 295ms default, 33ms with aux pass-through |
| Bass Extension (-10dB) | 31Hz |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth Codecs | aptX HD, aptX, AAC, SBC |
| Bluetooth Latency | 100ms |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 9.3" x 7" x 6.1" (236 x 178 x 155 mm) |
| Drivers | 2x 2.5" midrange, 2x 0.75" tweeters + 6.5"x9" subwoofer |
| EQ | No |
| Frequency Response | 30Hz - 20kHz (Manufacturer specified) |
| IP Rating | IP57 |
| Maximum SPL | 106dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | Yes (Brane app, up to 8 speakers) |
| Power Bank | No |
| Power Input | AC Power brick |
| Stereo | Yes |
| TWS | Yes |
| Weight | 7.7 lbs (3.5 kg) |
| Wi-Fi | Yes |
- Links
- Reviews, Comparisons and Sound Samples
- Alan Ross Reviews: This speaker left me shocked! Brane X, they said it defies the laws of physics! More from alanrossreviews →
- Alan Ross Reviews: Brane X vs JBL Xtreme 5: Maximum Bass, No Mercy
- Alan Ross Reviews: JBL Boombox 4 HUMILIATES Brane X?! Ultimate Bass Battle!
- Alan Ross Reviews: Minirig 2.1 or the Brane X or the Harman Kardon Go Play 3?
- mark: Brane X Speaker Review 2
- mark: Brane X Speaker Review
- Head-to-Head Comparisons