Short answer: the Bose Soundlink Flex 2nd gen on measured sound quality, the Ultimate Ears Boom 4 on price. The Bose Soundlink Flex 2nd gen ranks #33 of 136 medium speakers at $159. The Ultimate Ears Boom 4 ranks #88 at $105, $54 cheaper.
What the Bose Soundlink Flex 2nd gen offers: Pretty much identical sounding to the 1st gen Watch for: Not stereo. Warm sounding with overly boosted bass which drowns out midrange detail. Self drains the battery about 10% a week.
What the Ultimate Ears Boom 4 offers: IP67 rated, floats, and finally charges via USB-C instead of the older Booms’ Micro-USB. 15 hour battery. Customizable EQ and speaker-pairing via the UE app. Watch for: Not much improvement over the old ones. Weak bass extension and thuddy bass. Gets distorted above 90%
Buy the Bose Soundlink Flex 2nd gen if sound quality matters more than the price. Buy the Ultimate Ears Boom 4 if the price matters more than sound quality.
Specifications Side By Side
| Bose Soundlink Flex 2nd gen | Ultimate Ears Boom 4 | |
|---|---|---|
| Price | $159.00 | $105 |
| Ranked | #33 of 136 in Medium Size Portable Bluetooth Speakers | #88 of 136 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| 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) | - |
| Power Input | USB-C | USB-C |
| Stereo | No | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs / 586 g | 1.4 lbs / 620 g |
| Bluetooth Version | 5.3 | 5.1 |
| Dimensions | 7.9" x 3.5" x 2" (201 x 90 x 52 mm) | 7.2" x 2.9" x 2.9" (184 x 73 x 73 mm) |
| Aux Input | No | No |
| Drivers | 60mm full-range driver with passive radiators | 2x 1.57" (40mm) active drivers + 2x 1.81" x 2.57" (46.1 x 65.2mm) passive radiators |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | - |
| Digital Aux Input | No | No |
| Power Bank | - | No |
| Max Volume | - | 85dBC |
Related Speaker Comparisons
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- JBL Charge 5 vs Ultimate Ears Boom 3
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- Marshall Emberton II vs Ultimate Ears Boom 4
- Bose Soundlink Flex 2nd gen vs Bose SoundLink Color II
Prices on this page were last checked August 27, 2026 at 10:09 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: $159.00 Amazon eBay
Pros: Pretty much identical sounding to the 1st gen
Cons: Not stereo. Warm sounding with overly boosted bass which drowns out midrange detail. Self drains the battery about 10% a week.
Full Bose Soundlink Flex 2nd gen review and specifications →
| App | Yes |
|---|---|
| Aux Input | No |
| Battery Life | 12 hours (Manufacturer specified) |
| 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 |
| 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 →
- Oluv Patreon: Bose Soundlink Flex 2nd gen - sound demo
- Tô Thái Trí Hùng: Unbox & Sound Test - Bose Soundlink Flex 2
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen & Soundcore Motion 300 sound test
- Alan Ross: Hall of Fame classic vs latest Bose tech! More from alanrossreviews →
- CEONTHEMAKING: Bose Soundlink Flex 2nd Gen VS Marshall Emberton III - What’s NEW??
- Alan Ross - The Anti Shill!: Small speaker, mighty sound, The Flex gen 2 shatters physics!
- Reddit Search for Bose Soundlink Flex 2nd gen Review
- Head-to-Head Comparisons
- Bose Soundlink Flex 2nd gen vs Bose Soundlink Flex
- Bose Soundlink Flex 2nd gen vs Tribit Xsound Plus 2
- Bose Soundlink Flex 2nd gen vs JBL Charge Essential 2
- Bose Soundlink Flex 2nd gen vs Teufel Rockster XS
- Bose Soundlink Flex 2nd gen vs Soundcore Boom 3i
- Bose Soundlink Flex 2nd gen vs Soundcore Motion 100
- Bose Soundlink Flex 2nd gen vs JBL Charge 5
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- See all 82 comparisons
Ultimate Ears Boom 4: $105 Amazon eBay
Pros: IP67 rated, floats, and finally charges via USB-C instead of the older Booms’ Micro-USB. 15 hour battery. Customizable EQ and speaker-pairing via the UE app.
Cons: Not much improvement over the old ones. Weak bass extension and thuddy bass. Gets distorted above 90%
Full Ultimate Ears Boom 4 review and specifications →
| App | Yes |
|---|---|
| Aux Input | No |
| Battery Life | 15 hours (Manufacturer specified) |
| Bluetooth Version | 5.1 |
| Built in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 7.2" x 2.9" x 2.9" (184 x 73 x 73 mm) |
| Drivers | 2x 1.57" (40mm) active drivers + 2x 1.81" x 2.57" (46.1 x 65.2mm) passive radiators |
| EQ | Yes (via app) |
| IP Rating | IP67 |
| Max Volume | 85dBC |
| Omnidirectional | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| Weight | 1.4 lbs / 620 g |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Ultimate Ears Boom 4 vs Ultimate Ears Boom 3
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom
- Ultimate Ears Boom 4 vs Klipsch Groove/Heritage Groove
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom 2
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom 3
- Ultimate Ears Boom 4 vs Ultimate Ears Wonderboom 4
- Ultimate Ears Boom 4 vs Sony SRS-XE300
- Ultimate Ears Boom 4 vs Tribit Stormbox
- See all 74 comparisons