the grills

Leave on or off? I have a yellow lab.

I checked my George Foreman manual and is says a hot dog takes five minutes but nothing about a yellow lab? Did you mean a black lab? I know of a good Cajun catfish recipe...
If your or any speaker grills have frames, those would be a source of arbitrary reflection.
I don't think it will matter with Electras - on or off should sound equally good.