I run full legal limit sometimes, well on 80 meters usually, sometimes 40, and uh yep sometimes 20 meters. It did not matter what frequency I was on
I used to tear speakers up in the kids room, in the shack, and the shack is 700 feet from the house. It did not matter if I was on a yagi, a vertical or on the wire.
My pc in the study never got RFI.
I threw those dirt cheap speakers in tha garbage, the type of speakers that come with an all in one combination sale. speaker, keyboard, monitor and pc.
I replaced those cheap garbage speakers with logitech. Kids do not hear me anymore, I even streamed news cast video/audio on the pc in the shack while transmitting full legal limit, did not hear a scratch.
Exactly as C K stated, it is the speakers, or at least it was in this QTH.