ever heard a speaker have EMI interference? beep beep beep - bepbepbep- beep beep beep... and so on? from a cell phone?
with a shielded speaker.. this wont happen. Same goes for ballasts and sattelite cable. digital ballists are great.but you need to have a shielded ballast to prevent interference otherwise cable companies will be coming over with their meters and such asking questions
There is no such thing as a shielded ballets who ever is selling you that does not have a clue. Its like the poor people who buy 200 watt LED lights for two grand believing the sales man who tells them it would produce more bud then 2000 watts of hid lighting.
Its the cables that act like antennas either sending or receiving EMI RF noise, and the filters that my link provides has the shielding needed to stop those signals.
BTW testing for EMI and RF noise is as easy as tuning in static on your radio then turning off or on the source of the noise to see if the static increases or not. Or you can buy meters made for this and test at different frequencies, that's if you want to waste a few hundred dollars.