Unless the speaker manufacturer tells you to take them, the grills, off in the owners manual, leave them on. You don't know how many B&W and other speakers that have been damaged by people poking or touching fragile tweeter and mid drivers. Can the grills affect the sound, sure, but they shouldn't. If the speaker was designed with any thought then the grills used were included in the design and compromises were considered acceptable. You might not think they are and you might be right. But you have to be prepared to accept the consequences of removing the grills. If I owned better grades of speakers I would think twice about taking the grill off.