Short answer: the Marshall Willen II on measured sound quality, the Monster Bluetooth Speaker on price. The Marshall Willen II ranks #11 of 62 small speakers, rated 4.0/5, at $89.99. The Monster Bluetooth Speaker ranks #39, rated 3.0/5, at $19.99, $70 cheaper.
The Marshall Willen II is the better-sounding, deeper-bass option. A tiny waterproof strap on speaker with balanced sound, a long battery, and app EQ that clips easily onto a bag. Its bass reaches about 70Hz before falling 10dB, against 95Hz for the Monster Bluetooth Speaker. It is rated for 17 hours of battery against 6.5 for the Monster Bluetooth Speaker. It has an adjustable EQ, which the Monster Bluetooth Speaker lacks. The tradeoff: Not that deep of bass.
The Monster Bluetooth Speaker is the lighter pick. A very cheap, light waterproof travel speaker with USB-C charging, aux and microSD playback, and stereo pairing. At 0.4 lbs (185 g) it weighs much less than the Marshall Willen II at 0.8 lbs (360 g). It keeps a wired aux input, which the Marshall Willen II lacks. The tradeoff: Its tiny 36mm driver has very limited bass (about 95Hz at -10dB), elevated mids and rolled-off highs.
Buy the Marshall Willen II when sound quality outweighs the price for you, and the Monster Bluetooth Speaker when the price outweighs sound quality instead.
Looking for alternatives? See the complete Portable Bluetooth rankings.
A tiny waterproof strap on speaker with balanced sound, a long battery, and app EQ that clips easily onto a bag.
A very cheap, light waterproof travel speaker with USB-C charging, aux and microSD playback, and stereo pairing.
Prices on this page were last checked October 31, 2026 at 7:11 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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Specifications Side By Side
| Marshall Willen II | Monster Bluetooth Speaker | |
|---|---|---|
| Price | $89.99 | $19.99 |
| Ranked | #11 of 62 in Small Size Portable Bluetooth Speakers | #39 of 62 in Small Size Portable Bluetooth Speakers |
| App | Yes | No |
| Bass Extension (-10dB) | 70Hz | 95Hz |
| Battery Life | 17 hours (Manufacturer specified) | 6.5 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | Yes | No |
| IP Rating | IP67 | IPX7 |
| Party Mode | No | No |
| Power Bank | No | No |
| Power Input | USB-C | USB-C |
| Stereo | No | No |
| Omnidirectional | Pointing up | Pointing up |
| TWS | No | Yes |
| Weight | 0.8 lbs (360 g) | 0.4 lbs (185 g) |
| Aux Input | No | Yes |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| Bluetooth Version | 5.3 | 5.4 |
| Frequency Response | 75Hz - 20kHz (Manufacturer specified) | - |
| Charging Time | 2.5 hours | - |
| Drivers | 2” (51mm) full-range with dual passive radiators | 1.4” (36mm) full-range driver |
| Dimensions | 3.9” x 1.7” x 3.9” (99 x 43 x 99 mm) | Specifications vary by model |
| Amplifier Power | 10W | 5W |
| Digital Aux Input | No | No |
| Strap | Yes (built-in strap) | Yes (carabiner hook, suction cup) |
| MicroSD Playback | - | Yes |
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