Hey everyone

Well, a few years back a German exchange student stayed at my place, and she left this pair of speakers. They used to sound really nice, considering their small size. They were forgotten for maybe 2 years, and when I tried using them again I get this:
-A loud "pop" when I turn them on
-When on, there is a very low hum, very electrical sounding
-When I connect something to them, the volume is very low, and rises barely even if I crank the volume knob all the way up, all I get is a lot of crackling if I do this.

Here are some pictures.










It reads:
TS5725 A-B 230V/12VX2 1.5A
Thermal Fuse 130ºC
BC

I live in Mexico, we use 120v/60hz if I'm not mistaken. I suppose I need to change it so it works correctly with 120V? However, remember they used to work perfectly. Any help/suggestions greatly appreciated