Pop sound switching when sources, mute and turn off android head unit

Let me clarify it more to you
The speaker wires have the same pop sound but it’s too low to hear it, you will need to put your ear beside the speaker to hear it

However if you took this wires to loc then to amp the problem will appear

I believe the loc is not designed to handle the signal changes? Am I correct?
 
The LOC takes the signal anc reduces the level. The proportion of the pop should be the same. If it's virtually inaudible in the speaker, it should be just slightly louder through the amps. From your description of the pop through the RCA jacks, it's extremely loud.

Does this head unit have proper RCA output jacks like a normal head unit?
 
Is the proportion of the pop to audio significantly greater out of the RCAS than that of the audio out of the speakers? If that's true I think you should be able to use a PROPER LOC and get better results.

Are you 100% sure that the LOC you were using had transformers? <<< Transformers are important.

Was it connected directly to the positive and negative speaker wires for each channel of the LOC?
 
Okay so I'll focus now on the LOC solution by searching for a proper one with a transformers

Are the measures I did using the multimeter correct and clarify the pop problem?

And what are the other solutions if the LOC solution doesn't solve the problem?