These sit in different size classes, so this is not a straight ranking comparison. The Bose Soundlink Flex 2nd gen ranks #37 of 179 medium speakers by sound quality at $159; the Marshall Stockwell III ranks #84 of 120 large speakers by sound quality at $249.99.
The Bose Soundlink Flex 2nd gen is the lighter, tougher option. A small, rugged waterproof speaker with clear, well balanced mids, app EQ, aptX Adaptive and stereo pairing with a second unit. At 1.3 lbs (586 g) it weighs much less than the Marshall Stockwell III at 2.9 lbs (1.3 kg). It is rated IP67 against IP55 for the Marshall Stockwell III. It supports aptX Adaptive Bluetooth, which the Marshall Stockwell III lacks. The tradeoff: One Flex remains mono and cannot deliver genuine low-bass rumble; RTINGS also found the elevated treble can turn hi-hats and other high-frequency detail piercing.
The Marshall Stockwell III is the longer-running option. A stylish, rugged speaker with a very long battery you can swap yourself, a detailed app EQ, and power bank charging. It is rated for 40 hours of battery against 12 for the Bose Soundlink Flex 2nd gen. It keeps a wired aux input, which the Bose Soundlink Flex 2nd gen lacks. Watch for: Highs are recessed by default and need the treble control maxed to compensate, still lacking detail even then.
Buy the Bose Soundlink Flex 2nd gen at $159 for a medium speaker, or the Marshall Stockwell III at $249.99 for a large speaker instead.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Prices on this page were last checked November 7, 2026 at 7:34 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.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Marshall Stockwell III | |
|---|---|---|
| Price | $159.00 | $249.99 |
| Ranked | #37 of 179 in Medium Size Portable Bluetooth Speakers | #84 of 120 in Large Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 12 hours (Manufacturer specified) | 40+ hours (Manufacturer specified) |
| Built-in Microphone | Yes | - |
| EQ | Yes (3 band) | Yes (parametric, via app) |
| IP Rating | IP67 | IP55 |
| Party Mode | Yes (Bose Party mode) | - |
| Power Input | USB-C | USB-C |
| Stereo | No | Partially |
| Omnidirectional | No | Yes |
| TWS | Yes | No |
| Weight | 1.3 lbs (586 g) | 2.9 lbs (1.3 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 7.1” x 6.4” x 2.9” (180 x 162 x 74 mm) |
| Aux Input | No | Yes |
| Drivers | 60mm full-range driver with passive radiators | 1x 3” woofer, 2x 1.75” wide-band drivers |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | SBC, AAC, LE Audio with LC3 |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (detachable strap) |
| Frequency Response | - | 54Hz - 20kHz (Manufacturer specified) |
| Amplifier Power | - | 44W |
| Power Bank | - | Yes |
Related Speaker Comparisons
More top alternatives to Bose Soundlink Flex 2nd gen: