This and That:
Comes with a multifunctional USB cable with 3.5 mm, USB and micro USB plugs.
Small size. Good build quality.
Has got micro SD slot for music playback, along with an unusual line input (micro USB on one side and 3.5 mm on the other side of the cable). Has also got a headphone output (therefore it can also be used as Bluetooth receiver for a stereo system). Built-in FM radio (with no built-in antenna; the included cable serves as antenna).
Traditional on/off sliding switch. Unfortunately the speaker does not remember the volume setting; the default volume is already unnecessarily high.
Stupid volume key operation that's not very convenient at all: short press for skipping tracks, holding for volume adjustment.
FM radio has got only an auto-scan feature with no manual scan. Good signal strength, though.
Sound:
The LX-839 utilises a small wideband mono driver and nothing else (e.g. no passive radiator).
Tonality:
Not very surprisingly for the size, the lows' extension is poor. However, as opposed to using the speaker free-air, when it stands on a table or any other surface, the extension is surprisingly decent and 80 Hz are still audible (although obviously more quietly), which is quite positively surprising.
The tuning is a moderate v-shape - very mild upper bass/fundamental range lift, somewhat recessed mids, emphasised central and upper highs.
Ultimately, the speaker's highs are a bit too strong and lack some naturalness as the 5 kHz is a touch too forward, which leads to a somewhat metallic sound although without becoming unpleasant or overly bright.
So yeah, not too bad but the 5 kHz lift would have to be milder in order to achieve a more natural tuning.
Resolution:
No real separation or precision. Comparable to the quality of a better smartphone speaker but with superior extension and level stability.
Conclusion:
Okay sound but cumbersome volume control and it doesn't remember the volume setting either. One of Xiaomi's small stereo speakers would be the much wiser choice.