note: it also work with other portable music players via 3.5mm auxiliary input. see below.
The PureFi Anywhere 2 has a low incoming signal detection feature. When the system detects the lack of an incoming signal it will shut-off after 2 minutes or so. This insures that the battery is not drained when the device is not in use. The threshold of this circuit is such that it requires a reasonable incoming signal level to properly detect (this will vary with different media content).The solution - turn up the volume on the MP3 player and turn down the volume of the PureFi Anywhere 2.
