I know little about electronics in general. I wanted to connect Arduino, and play a tone using tone() through my home speakers.
I've used a 1/8'' audio jack and connect ground to ground and left/right to pin 2. Run it and it was too loud.
Then I read the specification and it says,
Input impedance = 20 kOhm
Input sensibility = 400mV +/- 50mV
Arduino sends 5V so that should be a lot. Did I damage my speaker? They still work.