Ultimate Ears Wonderboom 4 vs Bose Soundlink Flex 2nd gen

Last updated: August 16, 2026

Short answer: the Bose Soundlink Flex 2nd gen for better sound quality, the Ultimate Ears Wonderboom 4 for the lower price. The Bose Soundlink Flex 2nd gen ranks #33 of 136 medium speakers at $129.99. The Ultimate Ears Wonderboom 4 ranks #84 at $59.99, $70 cheaper.

What the Ultimate Ears Wonderboom 4 offers: A small, IP67-rated design that floats and charges over USB-C. Watch for: Its bass does not reach as deep as the top-ranked speakers and sounds a little thuddy; beyond USB-C, it is not much of an upgrade over the Wonderboom 3.

What the Bose Soundlink Flex 2nd gen offers: The second-generation Soundlink Flex keeps the rugged floating design, but it remains warm and bass-heavy and can self-drain its battery.

Buy the Ultimate Ears Wonderboom 4 if the price matters more than sound quality. Buy the Bose Soundlink Flex 2nd gen if sound quality matters more than the price.

Ultimate Ears Wonderboom 4 vs Bose Soundlink Flex 2nd gen

Specifications Side By Side

Ultimate Ears Wonderboom 4 Bose Soundlink Flex 2nd gen
Price$59.99$129.99
Ranked#84 of 136 in Medium Size Portable Bluetooth Speakers#33 of 136 in Medium Size Portable Bluetooth Speakers
Bass Extension (-10dB)--
Battery Life-12 hours (Manufacturer specified)
Bluetooth Latency--
Max Volume--
Power Input-USB-C
Stereo-No
Weight-1.3 lbs / 586 g
IP Rating-IP67
Bluetooth Version-5.3
Dimensions-7.9" x 3.5" x 2" (201 x 90 x 52 mm)
Drivers-60mm full-range driver with passive radiators
TWS-Yes
Party Mode-Yes (Bose Party mode)
App-Yes
EQ-Yes (3 band)
Built in Microphone-Yes
Power Bank--
Aux Input-No
Digital Aux Input-No
Bluetooth Codecs-SBC, AAC, aptX Adaptive

More useful head-to-heads from the same speaker class:

The Two Speakers In Full

Ultimate Ears Wonderboom 4: $59.99 Amazon

Ultimate Ears Wonderboom 4 ranking card

Pros: Small size.

Cons: Bass isn’t as deep as the top-ranked speakers and is a little thuddy. Not much improvement over the previous Ultimate Ears Wonderboom 3 besides the USB-C charging port.

App
Aux Input
Bass Extension (-10dB)
Battery Life
Bluetooth Latency
Bluetooth Version
Built in Microphone
Digital Aux Input
Dimensions
Drivers
EQ
IP Rating
Max Volume
Party Mode
Power Bank
Power Input
Stereo
TWS
Weight

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Bose Soundlink Flex 2nd gen ranking card

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.

AppYes
Aux InputNo
Battery Life12 hours (Manufacturer specified)
Bluetooth CodecsSBC, AAC, aptX Adaptive
Bluetooth Version5.3
Built in MicrophoneYes
Digital Aux InputNo
Dimensions7.9" x 3.5" x 2" (201 x 90 x 52 mm)
Drivers60mm full-range driver with passive radiators
EQYes (3 band)
IP RatingIP67
Party ModeYes (Bose Party mode)
Power InputUSB-C
StereoNo
TWSYes
Weight1.3 lbs / 586 g

As an eBay Partner, we may be compensated if you make a purchase.