Short answer: the Minirig 4 for sound quality and battery life, the Bose Soundlink Flex 2nd gen for durability and dependability. The Minirig 4 ranks #37 of 179 medium speakers at $229.95. The Flex 2nd gen ranks #7 at $159, $70.95 cheaper.
The Flex 2nd gen is a refinement, not a reinvention. Its clear, well-balanced midrange keeps voices and instruments intelligible, and the second generation adds a Bose app with 3-band EQ, better-placed controls, and stereo pairing with a second Flex. It also supports AAC and aptX Adaptive, not just SBC, making it a stronger wireless option than most small rivals. The honest tradeoff is that it remains mono, can’t produce genuine low-bass rumble, and RTINGS found the elevated treble can turn hi-hats piercing. Battery life is a modest 12 hours.
The Minirig 4 wins on modularity and stamina but carries real risk. It’s modular, so you can easily attach a subwoofer, it finally added USB-C charging, and it dynamically adjusts its sound depending on whether it’s facing forward or standing upward. Battery life is rated at 30 hours, well ahead of the Flex. But it calls itself only splash resistant with no official water rating, versus the Flex’s true IP67 rating that survives brief submersion. Its app is described as buggy, and it has reported reliability issues more often than any other speaker on the site.
Everything else matches: both charge over USB-C, include a built-in microphone, and support TWS pairing.
Buy the Minirig 4 if measured sound quality, longer battery life, and the ability to add a subwoofer matter most, and you can accept the durability and reliability tradeoffs.
Buy the Bose Soundlink Flex 2nd gen if you want genuine water resistance and a track record of reliability at a lower price, even with shorter battery life and less low-end extension.
Want more options? Browse the full Portable Bluetooth rankings.
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Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Minirig 4 | |
|---|---|---|
| Price | $159.00 | $229.95 |
| Ranked | #37 of 179 in Medium Size Portable Bluetooth Speakers | #7 of 179 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 12 hours (Manufacturer specified) | 30 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | Yes (3 band) | Yes |
| IP Rating | IP67 | Splash resistant |
| Party Mode | Yes (Bose Party mode) | - |
| Power Input | USB-C | USB-C |
| Stereo | No | No |
| Omnidirectional | No | Pointing up |
| TWS | Yes | Yes (Bluetooth or cable) |
| Weight | 1.3 lbs (586 g) | 1.2 lbs (550 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.0 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 4” x 2.9” (101.6 x 73 mm) (diameter x height) |
| Aux Input | No | Yes |
| Drivers | 60mm full-range driver with passive radiators | 70mm custom driver |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | AAC, SBC |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | - |
| Aux Latency | - | 0ms |
| Bass Extension (-10dB) | - | 56Hz |
| Bluetooth Latency | - | 60ms |
| Maximum SPL | - | 106dB (measured by Alan Ross Reviews) |
| Power Bank | - | Yes (USB-C) |
| Frequency Response | - | 60Hz - 18kHz (Manufacturer specified) |
| Amplifier Power | - | 50W |
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