Thank you,
@PristineSound, hmm,
Speaker Test/Measures are done with Grills Off, aren't they, unless the Grills are fixed and cannot be removed. So hopefully, the Grills are, or be considered as, Transparent and not just for Shiping/People/Animal Protection, reasonable, although Test/Measure would be required, wouldn't it?
When a Speaker is Tested/Measured, with Grill/s on, then the Grills can be considered as a Wave Guide, reasonable?
Perhaps those useing Grills On, also utilise DSP/etc. The Room (also the Listener/s) can be considered as a (Dominant) consideration/s, can't they?
Certainly when Drivers are Tested/Measured it is done without Grills, aren't they?