My concern too Bigjoe, I started thinking about this after a friend told me he had just broken the post off a speaker grill, he always listens with grilles off. But I will probably a least give it a listen with my grilles off. I asked my manufacturer Spendor, they said their fabric does not defract high frequency, but said some owners prefer the grilles off and encouraged me to try it both ways. I posted the same question on Audio Assylum and got a good response from 'Bobby'.