Short answer: the Bose Soundlink Flex 2nd gen. It ranks #37 of 175 medium speakers by sound quality, rated 3.8/5, at $99.99; the Ultimate Ears Boom 3 ranks #114, rated 2.9/5, and costs $134.99, so there is not much of a tradeoff to weigh.
The Bose Soundlink Flex 2nd gen is the better-sounding option. A very portable 1.3 lbs (586 g), IP67-rated speaker with a clear, well-balanced midrange that keeps voices and instruments intelligible. It supports aptX Adaptive Bluetooth, which the Ultimate Ears Boom 3 lacks. It charges over USB-C rather than Micro USB. Watch for: 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 case for the Ultimate Ears Boom 3: Rich and warm bass without muddying mix, crisp highs, excellent 15-hour battery life, stable Bluetooth connectivity, IP67 rated and floats, rugged fabric shell, can pair up to 150 speakers via PartyUp. It plays in stereo from a single unit, unlike the Bose Soundlink Flex 2nd gen. The tradeoff: Not stereo, barely any bass, recessed treble.
Buy the Bose Soundlink Flex 2nd gen. It is rated higher for sound quality than the Ultimate Ears Boom 3 and costs less, which makes it the one to get unless you need something the other one does better.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Ultimate Ears Boom 3 | |
|---|---|---|
| Price | $99.99 | $134.99 |
| Ranked | #37 of 175 in Medium Size Portable Bluetooth Speakers | #114 of 175 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes (Ultimate Ears BOOM & MEGABOOM app) |
| Battery Life | 12 hours (Manufacturer specified) | 15 hours (Manufacturer specified) |
| Built-in Microphone | Yes | No |
| EQ | Yes (3 band) | Yes (via app) |
| IP Rating | IP67 | IP67 |
| Party Mode | Yes (Bose Party mode) | Yes (PartyUp up to 50 speakers) |
| Power Input | USB-C | Micro USB |
| Stereo | No | Yes |
| Omnidirectional | No | Yes |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (586 g) | 1.3 lbs (608 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 4.2 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 7.2” x 2.9” (184 x 73 mm) |
| Aux Input | No | No |
| Drivers | 60mm full-range driver with passive radiators | 2x 2” active drivers + 2x 2” x 4” passive radiators |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | SBC |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | Yes (built-in loop) |
| Bass Extension (-10dB) | - | 91Hz |
| Maximum SPL | - | 87dB (Manufacturer specified) |
Related Speaker Comparisons
More worthwhile head-to-heads for Bose Soundlink Flex 2nd gen:
- Bose Soundlink Flex 2nd gen vs EarFun Uboom L
- Bose Soundlink Flex 2nd gen vs Soundcore Motion 300
- Bose Soundlink Flex 2nd gen vs Soundcore Motion+
- Bose Soundlink Flex 2nd gen vs Soundcore Boost “upgraded” 2021
- Bose Soundlink Flex 2nd gen vs Minirig 4
Prices on this page were last checked October 12, 2026 at 4:13 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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The Two Speakers In Full
Bose Soundlink Flex 2nd gen: $99.99 Amazon $99.99 eBay
Older model: the Bose Soundlink Flex (ranked lower, rated 3.8/5). See every Bose SoundLink Flex, Micro, Max and Plus generation.
Same family: the Bose SoundLink Max (larger model, rated 4.3/5), the Bose Soundlink Micro 2 (larger model, rated 3.6/5) and the Bose SoundLink Plus (larger model, rated 4.2/5).
Pros: A very portable 586g, IP67-rated speaker with a clear, well-balanced midrange that keeps voices and instruments intelligible. The second generation adds a Bose app with 3-band EQ, better-placed controls and stereo pairing with another Bose Soundlink Flex 2nd gen. It supports AAC and aptX Adaptive in addition to SBC, making it a stronger wireless option than most small rivals.
Cons: 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 claimed battery life is only 12 hours, and some owners report accelerated standby drain after firmware updates. It is expensive for its size, so the added app and codec support, not a transformational sound upgrade over the original, are the main reasons to choose it.
Full Bose Soundlink Flex 2nd gen review and specifications →
| Released | Sep 2024 (2 years ago) |
|---|---|
| App | Yes |
| Aux Input | No |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive |
| Bluetooth Version | 5.3 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) |
| Drivers | 60mm full-range driver with passive radiators |
| EQ | Yes (3 band) |
| IP Rating | IP67 |
| Omnidirectional | No |
| Party Mode | Yes (Bose Party mode) |
| Power Input | USB-C |
| Stereo | No |
| Strap | Yes (built-in loop) |
| TWS | Yes |
| Weight | 1.3 lbs (586 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen vs Flex More from Oluv’Sone →
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen & Soundcore Motion 300 sound test
- Oluv Patreon: Bose Soundlink Flex 2nd gen - sound demo
- Alan Ross: Hall of Fame classic vs latest Bose tech! More from alanrossreviews →
- Alan Ross - The Anti Shill!: Small speaker, mighty sound, The Flex gen 2 shatters physics!
- Alan Ross - The Anti Shill!: DBSONO X-Blast F37 vs Bose Soundlink Flex 2 - They all want to be me 😊
- Mateusz Cholewa: JBL Charge Essential 3 SE vs BOSE SoundLink FLEX 2 More from Mateusz Cholewa →
- CEONTHEMAKING: Bose Soundlink Flex 2nd Gen VS Marshall Emberton III - What’s NEW?? More from CEONTHEMAKING →
- Tô Thái Trí Hùng: Unbox & Sound Test - Bose Soundlink Flex 2
- Musou1: JBL flip 7 vs KEF muo vs Bose flex 2
- Head-to-Head Comparisons
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Ultimate Ears Boom 3: $134.99 Amazon $134.99 eBay
Newer model: the Ultimate Ears Boom 4, ranked higher, rated 2.9/5, released Jun 2024. See every Ultimate Ears Wonderboom, Boom and Megaboom generation.
Pros: Rich and warm bass without muddying mix, crisp highs, excellent 15-hour battery life, stable Bluetooth connectivity, IP67 rated and floats, rugged fabric shell, can pair up to 150 speakers via PartyUp. Measured bass extension of 91Hz (-10dB).
Cons: Not stereo, barely any bass, recessed treble. You can tell from the micro USB that they are just feeding you the same crap hardware over and over, this is inexcusable for a product released in 2021. Lots of mentions of failing batteries on amazon. Not technically a 360 speaker, only front and rear.
Full Ultimate Ears Boom 3 review and specifications →
| Released | Sep 2018 (8 years ago) |
|---|---|
| App | Yes (Ultimate Ears BOOM & MEGABOOM app) |
| Aux Input | No |
| Bass Extension (-10dB) | 91Hz |
| Battery Life | 15 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 4.2 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 7.2” x 2.9” (184 x 73 mm) |
| Drivers | 2x 2” active drivers + 2x 2” x 4” passive radiators |
| EQ | Yes (via app) |
| IP Rating | IP67 |
| Maximum SPL | 87dB (Manufacturer specified) |
| Omnidirectional | Yes |
| Party Mode | Yes (PartyUp up to 50 speakers) |
| Power Input | Micro USB |
| Stereo | Yes |
| Strap | Yes (built-in loop) |
| TWS | Yes |
| Weight | 1.3 lbs (608 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Ultimate Ears Boom 3 vs Ultimate Ears Boom 4
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- See all 99 comparisons