It doesn't seem that a 60A panel would necessarily contribute less interference than a 400A panel just from the amount of current. The difference would be that more interference-causing things can be plugged into the number of outlets coming from a 400A panel than from the smaller amount of outlets plugged into a 60A panel.

(I use the term outlets as representative. Of course all the outputs of a 400A panel don't go to outlets.)

buzz's comment about the strength of the magnetic field reminds me of this little hospital oopsie:









And of course there's this, too: