Soundstream Technologies RUB1.2500D - Manual (Page 15)

Caution:
Please do not plug in or unplug RCA
Plugs to the amplifier inputs while
the amplifier is turned on. Doing
so is potentially harmful to the amplifier
by allowing RF(radio frequencies)
into the amplifier, causing
instability, during the brief period while
the RCA shield is not connected, and the
hot is connected. Only plug in or unplug
RCA plugs with the amplifier off as
Standard practice with all audio equipment.