Bose SoundLink Flex (2nd Gen) Review: A Codec Update

The original SoundLink Flex became one of the best-selling portable speakers Bose has made, and the second generation is a quiet update rather than a reinvention. The drivers are unchanged. The case is unchanged. What changed is a short list — and whether that list matters is the entire buying decision.

Four things, and only four:

• Bluetooth moves to 5.3, adding the aptX codec alongside AAC. The first generation was limited to SBC, the most basic option, which was the one complaint audiophiles consistently raised. Note that aptX requires the connected device to support Snapdragon Sound.
• A three-band equaliser arrives in the app, where before there was none.
• A new shortcut button on the speaker, assignable to Spotify Tap, your phone's voice assistant, or audio chaining.
• Multipoint connection management in the app.

What did not change: the acoustic architecture is still a single full-range driver with a pair of passive radiators, the flat profile and silicone body are carried over, and the IP67 rating stays.

One catch on that shortcut button. The audio chaining it enables — pairing two speakers for stereo, or syncing several — is not backwards compatible with the first-generation Flex. If you own one already and hoped to pair it with a new one, you cannot.

With identical internals, the sound is effectively identical too. Independent measurement found nothing meaningful separating it from its predecessor beyond a slightly more recessed upper-midrange and treble, which barely alters the signature.

That signature is energetic, with a pronounced taste for bass and extreme treble. For a case this compact the low-end extension genuinely impresses: bass reproduces fully down to 70 Hz without hollowing out the upper bass, and it is both deep and punchy, with controlled, detailed lows and realistic kick-drum impact. The soundstage is wide for the size.

The limits are the ones you would expect from a simple acoustic layout. Bass tends to bleed slightly into the lower midrange, the extreme treble can sound artificial, and dynamics compress at high volume. A second independent assessment reached the same overall conclusion by a different route, praising the richness and noting Bose Position IQ — which adjusts equalisation according to how the speaker is oriented — as delivering a consistent result whichever way you stand it.

Here is the genuinely strange finding, and both assessments independently confirmed the direction of it: latency got worse, not better, despite the newer codecs.

The two measurements differ. One recorded 250 ms. The other measured 179 ms, against 165 ms for the first-generation model. Both figures point the same way — the older, technically inferior SBC-only speaker is the more responsive one.

In practice this only matters for video without compensation or for competitive gaming; streaming services automatically resync audio and picture. But if you specifically bought into the newer codecs expecting lower lag, that is not what they deliver here.

The silicone body and metal acoustic grille give a genuine impression of solidity, and the IP67 rating means it resists dirt and survives immersion in fresh water at 1 metre for 30 minutes. It also floats, which a JBL Flip 7 does not — a small thing until it goes in a pool.

It is light and compact enough for a small bag, can be carried on one finger by the thick integrated strap, and stands either flat or upright thanks to purpose-built supports. Grip on the surface it sits on is excellent, though standing upright it can be unsettled on steeper inclines.

Bose quotes 12 hours. Timed testing recorded 12 hours 30 minutes at 50% volume, a comfortable listening level — so the claim holds and then some.

Push it harder and the picture changes sharply: at a louder 79 dB, it ran for only 6 hours 40 minutes. Budget accordingly if you play it loud outdoors.

The rubber control interface remains intuitive and complete enough to run the speaker without opening the app. One regression: the buttons sit slightly more recessed than on the first generation, so you have to press noticeably harder to feel the confirmation click. Voice prompts help you navigate, though translation quality occasionally undermines them.

The app adds multipoint source management, the three-band equaliser, shortcut-button customisation, auto power-off timing and voice-guide language.

As a speakerphone it performs well close up and indoors, capturing the voice clearly with slight saturation in the high frequencies. At 5 metres capture becomes choppy as soon as you speak quickly. Outdoors at 2 metres it is fine apart from minor wind interference.

There is no wired audio at all — the USB-C port does not carry audio, and there is no 3.5 mm input. For a speaker positioned as rugged and go-anywhere, that remains a genuine limitation.

Buy it if you are coming from something older or from a rival, and you want a compact speaker with class-leading bass extension for its size, real waterproofing, and a battery that comfortably clears twelve hours at sensible volume.

Do not upgrade from the first-generation Flex expecting a meaningful change. The sound is the same, the latency is slightly worse, and the stereo pairing will not work with the speaker you already own. The upgrade is codecs and an equaliser — worth it only if those specific gaps were bothering you.

Truthful Reviews has not tested this speaker. The measurements above come from published testing by two independent European publications, both covering this exact model — the second-generation Flex, not the original or the SE variant — and both stored against this page as approved editorial provenance in machine-readable form. Where the two disagree, as on measured latency, both figures are given.

We are not quoting a UK price. Amazon UK listings for the standard second-generation Flex showed prices on search results but no working buy box on any product page, and the cheapest listing was Amazon Resale stock — open-box rather than new — so it was excluded on condition grounds. The SE variants in the same results are a different model and were not substituted.

Rather than print a figure whose seller and condition we cannot stand behind, we have omitted it. Check Amazon UK availability or search on Amazon US