Alternator whine and eliminating it

[EmilA]

In my mind, alternator whine is caused by the power leads running to close to the speaker cables. However doing some research into it, seems like that is not the sole cause, and not the sole fix either.

Google has lead me to these sites in an attempt to investigate and hopefully remove it altogether. Has anyone done something similar and removed it?
The links all have a similar theme to address which is making sure the equipment all have a good solid earth connection. I can't recall how the headunit was in the car 8 years ago as it wasn't working properly then, I want to say there was abit of a whine but the car had more than one problem then ha.

https://audiorevamp.com/alternator-whine-car-audio...
https://www.caraudio.com/threads/noise-troubleshoo...
https://itstillruns.com/remove-alternator-whine-ca...