The A2+ is equipped with a power-saving circuit that turns off the speaker's final stage amp. The A2+ has a idle mode which activates right after you stop playing music. Due to this power-saving function, we recommend that the speakers stay on all the time. It's worth mentioning that all of this is instantaneous (as soon as the input signal stops and it disengages automatically once an input in reintroduced), so there shouldn't be a noticeable delay when resuming audio