Short answer: the Luna if balance matters, the Flex 2nd gen if price does. The Luna ranks #37 of 172 medium speakers against the Flex 2nd gen’s #26, for $131.99 more.
Neither speaker is neutral, but the Luna keeps its bass in check better. Its pros describe it as pretty balanced besides the boosted bass, while the Flex 2nd gen’s cons go further: warm sounding with overly boosted bass that drowns out midrange detail. Both measure mono rather than stereo, and the Luna’s cons note its own bass boost still leaves it less detailed than higher ranked speakers in the class.
The Flex 2nd gen has one known reliability quirk. Its cons note it self-drains the battery about 10% a week, something to plan around if you store it between uses. Its pros note it sounds pretty much identical to the original Flex, so if you already own that model this is not a sound upgrade.
What the Flex 2nd gen adds that the Luna lacks:
- An app with a 3-band EQ, versus no app or EQ on the Luna at all.
- Bose Party Mode for linking multiple Bose speakers.
- aptX Adaptive codec support and a built-in microphone, both missing on the Luna.
What the Luna adds: USB playback and a measured 57Hz bass extension, giving a documented number where the Flex 2nd gen has none listed.
Buy the Luna if you want the more balanced sound of the two and don’t mind going without an app or EQ.
Buy the Flex 2nd gen if budget is the priority, or if you want app-based EQ control and Bose Party Mode, and can tolerate a bass-heavy signature and the battery’s self-drain.
Want more options? Browse the full Portable Bluetooth rankings.
A very portable 586g, IP67-rated speaker with a clear, well-balanced midrange that keeps voices and instruments intelligible.
Amazon $159.00 eBay
A 1.13 kg portable with IP67 waterproofing, 12-hour battery life and fairly balanced sound apart from boosted bass.
Amazon $290.99 eBayPrices on this page were last checked October 16, 2026 at 5:46 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
| Bose Soundlink Flex 2nd gen | Harman Kardon Luna | |
|---|---|---|
| Price | $159.00 | $290.99 |
| Ranked | #37 of 172 in Medium Size Portable Bluetooth Speakers | #26 of 172 in Medium Size Portable Bluetooth Speakers |
| App | Yes | No |
| Battery Life | 12 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| Built-in Microphone | Yes | - |
| EQ | Yes (3 band) | No |
| IP Rating | IP67 | IP67 |
| Party Mode | Yes (Bose Party mode) | - |
| Power Input | USB-C | USB-C |
| Stereo | No | No |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (586 g) | 2.5 lbs (1.13 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 8.3” x 3.1” x 3.1” (210 x 78 x 80 mm) |
| Aux Input | No | No |
| Drivers | 60mm full-range driver with passive radiators | 48mm x 90mm woofer, 20mm tweeter |
| Bluetooth Codecs | SBC, AAC, aptX Adaptive | SBC |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | - |
| Bass Extension (-10dB) | - | 57Hz |
| MicroSD Playback | - | No |
| USB Playback | - | Yes |
| Frequency Response | - | 60Hz - 20kHz (Manufacturer specified) |
| Amplifier Power | - | 40W |
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