JBL Synchros S400BT Bluetooth Headphones

As a part of the Harmann International Group, JBL is able to call on the significant resources of the firm - including dedicated headphone brand AKG - for technical knowhow. The Synchros S400BT is the most upmarket of three Bluetooth-equipped versions and also the largest. This implies that it and the Panasonic offering vie to function as the largest of the layouts in the evaluation.

The large dimensions mean the S400BT is a folding on-ear design, but the earpad covers the entire ear and provides a good degree of isolation from the outside world. Each enclosure houses a single 40mm driver and like a number of other layouts in the test, the wired connection terminates in a 2.5mm jack connection. The S400BT is nicely stipulated in Bluetooth conditions offering NFC and aptX support' touch to pair1 functionality.

The JBL has some styling touches that might exasperate those of us settling into middle age

- like the detailing to really make the driver enclosures look like loudspeaker baskets

- but in a discipline of models that glow and make fearless use of some unexpected colours, the black finish of the review pair is fairly limited. A white version is available for those that need to make more.

This is not to imply that there aren't some bold flourishes. The big JBL logo on each side lights upwards depending on what the S400BT is doing at any one time. This play and also acts as a touchpad for volume, track skip /pause plus it functions better than expected, although not as effectively as the buttons to the Panasonic or Sony models.

The fit and finish is strong as well as the choice of substances is usually good. The earpads that are big make the S400BT comfortable to wear for extended intervals, even though the 275g weight is towards the higher end. An excellent quality - if quite big - carry case is supplied together with USB lead and a 1m sound cable.

Sound quality

The JBL is a bit less sensitive than the group average, but nevertheless proves an easy enough load for the DacMagic XS to reach the test level. Connected via cable, it manages to do a lot of things right. JBL makes no secret that its models are expressed for use on the move and this typically results bass than a classic home headphone, but the S400BT incorporates the low end that is substantial into the rest of the frequency response commendably well. This allows it to seem in control with the 24/96 Floyd track and large. The operation stays civilised at high levels and is not easily provoked into aggression or harshness.

What actually gives an edge over most of the rival designs to the JBL is that it manages to make use of this powerful sound as refined but fun at precisely the same time to come across. The Rival Sons are delivered with assurance and drive while Kraftwerk as well as the final Mazzy Star evaluation piece demonstrate the S400BT to be really capable of both large scale and inviting tonality at once. They are really marked by just an incredibly little depth to the lower midrange that seems to hide some finer details of this type down against dedicated dwelling cans.

It may be a touch gimmicky

JBL Synchros S400BT Bluetooth Headphones photo