Because I have a 2 year old and a 4 year old (18 months apart, yes I'm tired), I use the the grills supplied with my speakers. By leaving them on, I feel like the drivers are much less likely to get poked. When I first got my contours, I would pull off the grills before I settled in to a listening session (late at night, kids sleeping away). I really had not done much grill on/off sound comparisons, but I figured they would sound better unimpeded by a fabric cover, plus I really prefer the looks of the speakers sans grills and it's nice to see the drivers in all their glory occassionally. However, after a few weeks of this I got lazy and started just leaving the grills on all the time. So I've been listening for months now with the grills permanently affixed. What I'm saying is, I'm very familiar with the sound of these speakers with the grills in place so I would be sensitive to any change. Recently I took off the grills for a listening session and it really seemed to make a difference to the openness. A very slight increase in livelyness. So now I'm leaving them off permanently and just taking my chances with the kids.