Personal experiences and learnings....
If I have a great balanced transformer and kick ass ground, it's still was not enough to clean up the mains.
That its important to restart the OS on the O if I pull the ethernet from the T router due to a storm.
That I need to restart the OS on the O as a routine, once a week.
I learned that I still need to shut down and restart my house router that connects to the T router to get the best results.
(The modem not as often)
I learned to scan and choose the least noisy wifi channels to get the best sound ...Some how this appears to have an effect.
I learned that properly torqued drivers are mandatory and the interval of follow up cant be 6 months.
Of course your mileage and tolerance to such minutia may vary.