Hello friends, this speaker has brought it to me and the first thing I have seen is the fuse and the fuseholder totally refilled .. to test the source, which is a toroidal transformer of 220v input and 25v output in two channels .. good I have put a lamp in series .. and the device works, until there is everything right ... the doubt is that when I go up the volume the lamp is going on to the rhythm of the music, against more volume but it turns on .. I do not know if it is normal .. the fuse is placed in the primary input of the toroidal transformer .. my question is if that means that when the volume fuses the fuse ... and if that is the fault, what can be broken ?, 25 volts of alternating current enters the plate, then it has the diode bridge, so I am surprised that the volume signal reaches the primary one. Greetings, I thank you for your collaboration.