Short answer: the Tronsmart Mirtune S100. It ranks #97 of 179 medium speakers by sound quality, rated 3.1/5, at $79.99; the Ultimate Ears Boom 4 ranks #113, rated 2.9/5, and costs $114.99, which makes this an easy call rather than a real tradeoff.
The Tronsmart Mirtune S100 is the longer-running option. A waterproof speaker with long battery life for outdoor and casual listening. It is rated for 20 hours of battery against 15 for the Ultimate Ears Boom 4. It keeps a wired aux input, which the Ultimate Ears Boom 4 lacks.
The Ultimate Ears Boom 4 is the lighter pick. A tough waterproof speaker that floats, with USB-C charging, app EQ and pairing with other UE speakers. At 1.4 lbs (620 g) it weighs much less than the Tronsmart Mirtune S100 at 3 lbs (1.36 kg). The tradeoff: Not much improvement over the old ones.
Buy the Tronsmart Mirtune S100. It is rated higher for sound quality than the Ultimate Ears Boom 4 and costs less, so only choose the other one for a particular feature it does better.
Want more options? Browse the full Portable Bluetooth rankings.
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.
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Specifications Side By Side
| Tronsmart Mirtune S100 | Ultimate Ears Boom 4 | |
|---|---|---|
| Price | $79.99 | $114.99 |
| Ranked | #97 of 179 in Medium Size Portable Bluetooth Speakers | #113 of 179 in Medium Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | ~64Hz | - |
| Battery Life | 20 hours (Manufacturer specified) | 15 hours (Manufacturer specified) |
| Built-in Microphone | Yes | No |
| IP Rating | IPX7 | IP67 |
| Stereo | Partially | Yes |
| Omnidirectional | No | No |
| Weight | 3 lbs (1.36 kg) | 1.4 lbs (620 g) |
| Wi-Fi | No | - |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.1 |
| Dimensions | 9.1” x 3.5” x 3.9” (231 x 88 x 100 mm) | 7.2” x 2.9” x 2.9” (184 x 73 x 73 mm) |
| Frequency Response | 50Hz - 20kHz (Manufacturer specified) | - |
| Amplifier Power | 50W | - |
| Drivers | 20W drivers | 2x 1.57” (40mm) active drivers + 2x 1.81” x 2.57” (46.1 x 65.2mm) passive radiators |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC | SBC |
| App | Yes | Yes |
| Aux Input | Yes | No |
| EQ | Yes | Yes (via app) |
| TWS | Yes | Yes |
| Power Input | USB-C | USB-C |
| Power Bank | - | No |
| Maximum SPL | - | 85dBC (Manufacturer specified) |
| Strap | - | Yes (built-in loop) |
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