Short answer: the Marshall Kilburn II, unless you need serious water resistance. It ranks #36 of 78 large portable speakers against the ULT Field 5’s #41, and it costs $81 less, so there is not much of a tradeoff on paper.
Sound character is a genuine style difference, not just a quality gap. The Kilburn II pairs a 20W Class D amp with dual 8W tweeters and is built to thrive with rock music, but its cons note boosted upper bass, a peak in the upper mids, and less detail and depth than competitors offer. The ULT Field 5 leans even harder into bass, with reviews describing it as energetic and dynamic with substantial low end and two ULT modes to dial in a deeper or punchier presentation, but the same reviews note the upper mids and highs come out subdued with limited stereo separation, and that deep bass is less authoritative than the cabinet size suggests.
Water resistance is where the Sony pulls far ahead. The Kilburn II is rated IPX2, enough for light drips but not much else, while the ULT Field 5 is IP67, dust tight and able to survive submersion. The ULT Field 5 also adds a 10 band app EQ, LDAC and AAC codec support, Party Connect pairing, and USB-C power bank output, none of which the Kilburn II offers.
What the Kilburn II adds instead: a leather carry handle and reinforced corners built for handling and looks rather than water exposure, and quick charging that gets 3 hours of playback from a 20 minute top-up.
Buy the Marshall Kilburn II if you want the classic look and rock-friendly sound and can keep it away from water and rain.
Buy the Sony ULT Field 5 if you need genuine water and dust protection, app-based EQ control, or multi-speaker pairing, and don’t mind paying a bit more for them.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Marshall Kilburn II | Sony ULT Field 5 | |
|---|---|---|
| Price | $279.00 | $198 |
| Ranked | #36 of 78 in Large Size Portable Bluetooth Speakers | #41 of 78 in Large Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Bass Extension (-10dB) | ~58Hz | - |
| Battery Life | 20 hours (Manufacturer specified) | 25 hours (Manufacturer specified) |
| IP Rating | IPX2 | IP67 |
| Weight | 5.5 lbs (2.49 kg) | 7.3 lbs (3.3 kg) |
| App | No | Yes |
| Bluetooth Codecs | SBC | SBC, AAC, LDAC |
| Built-in Microphone | Yes | Yes |
| EQ | No | Yes (App + ULT button) |
| Party Mode | No | Yes (Party Connect up to 100 speakers) |
| Power Bank | No | Yes (USB-C) |
| Power Input | USB-C | USB-C |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Amplifier Power | 36W | 27W |
| Dimensions | 9.6" x 6.4" x 5.5" (243 x 162 x 140 mm) | 12.6" x 5.7" x 4.9" (320 x 144 x 125 mm) |
| Drivers | 1x 4" (102mm) woofer + 2x 20mm dome tweeters | 2x 46mm tweeters + 1x 79mm x 107mm woofer |
| Maximum SPL | 102dB (Manufacturer specified) | - |
| Digital Aux Input | No | No |
| Bluetooth Version | 5.0 | 5.3 |
Related Speaker Comparisons
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Prices on this page were last checked September 23, 2026 at 11:24 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 II: $279.00 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 |
| Bluetooth Version | 5.0 |
| 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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Sony ULT Field 5: $198 Amazon eBay
Pros: A tough 3.3kg portable with IP67 protection, LDAC/AAC support, aux input, a 10-band app EQ, Party Connect, USB-C power-bank output and a claimed 25-hour battery. Reviews find it energetic and dynamic with substantial bass, enough volume for a yard, and two ULT modes that let bass-focused listeners choose a deeper or punchier presentation.
Cons: It prioritizes bass and loudness over fidelity: reviews find the upper mids and highs subdued, with limited stereo separation and soundstage depth. Deep bass is less authoritative than the enclosure suggests, and the loud confirmation tone when pressing the ULT button is an unnecessary annoyance. Use the app EQ and audition it before buying for detail-focused music.
Full Sony ULT Field 5 review and specifications →
| Amplifier Power | 27W |
|---|---|
| App | Yes |
| Aux Input | Yes |
| Battery Life | 25 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC, AAC, LDAC |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 12.6" x 5.7" x 4.9" (320 x 144 x 125 mm) |
| Drivers | 2x 46mm tweeters + 1x 79mm x 107mm woofer |
| EQ | Yes (App + ULT button) |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Party Connect up to 100 speakers) |
| Power Bank | Yes (USB-C) |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| Weight | 7.3 lbs (3.3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Danny Pops: Don’t TOUCH that ULT Button! Sony ULT Field 5 Review More from DannyPops →
- Mark Ellis Reviews: Sony just changed summer sound 🤨 | Sony ULT Field 5 & 3 Review
- Dominik Reviews: Sony ULT Field 5 vs JBL Xtreme 4 - Outdoor Sound Test - Sony shines or not? More from Dominik Reviews →
- Joy & Oluv’Sone: Sony ULT Field 5 vs Anker SoundCore Boom 2 - listening test More from Oluv’Sone →
- Head-to-Head Comparisons