The best way to solve line noise is with x10 testing equipment.
With or without x 10 testers, you should do the following,....
in the entire property;
1. remove all plug strips - use 6 plex outlets instead.
2. remove all screw in Fl lighting. use incandescent lamps or Low voltage.
3. remove any lutron maestro or diva dimmers
4. remove any radio ra dimmers.
5. remove any apc computer back up type devices
6. filter all laptop power in the entire property
7. filter all LCD LED or Plasma screen tvs
8. filter all DVRs
9. remove any HID or commercial lighting
10. if your house is larger than 1300 sq feet make sure you have a coupler repeater at each panel on the property.
11. Remove all surge protection plug strips - use whole house surge protection at panel instead.
12. if the house has solar it can be filtered.
13. filter all laser printers - use act 120 filters
14. Battery chargers in garage must be unplugged.
15. unplug or filter all inverters electronic transformers etc.