I've an Sony SRS-D8 Active Speaker System one and half year old. It produces an constant hum or hiss whatever it is called as whenever it is turned on & whether it is connected to Dell Studio 15 laptop or to an Sony Walkman or just left disconnected without any input source & kept on. I don't know whether it used to produce that hum or hiss when it was brand new or not but yesterday I took my ears very close to the speakers found that all the speakers including subwoofers & tweaters produce hum or hiss noise.
Is it normal for an Active an Speaker System to produce this audible hum or hiss when it is idle? Or is it due to the constant fluctuation in power? Or Is something broken in speakers?
Note: It has 2 pin power plug & When the speakers are on laptop will be in sleep mode with power switch in Off position. Hum or hiss doesn't vary with volume & it is constant through out.