Short answer: the Marshall Kilburn II, unless you need serious water resistance. It ranks #42 of 120 large portable speakers against the ULT Field 5’s #59, and it costs $129 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.
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Specifications Side By Side
| Marshall Kilburn II | Sony ULT Field 5 | |
|---|---|---|
| Price | $219.00 | $348.00 |
| Ranked | #42 of 120 in Large Size Portable Bluetooth Speakers | #59 of 120 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 | Yes | 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 |
| Strap | Yes (built-in strap) | Yes (detachable shoulder strap) |
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