Yes, grilles make a difference! On some speakers more than others, as some are engineered for sound with the grilles on(very few), and the actual fabric used may or may not be acoustically transparent. If the grilles are not detachable, then make sure you don't kill your sound by putting any old cloth over your drivers. Also, try to make your significant other part of the buying process in the first place, and avoid many problems. Not to mention, audio enthusiast or not, another set of ears can't hurt, and you can educate those ears to be a great asset, if she is not very experienced in audio comparisons. Heck, you may even want to say nothing and get her uninfluenced(by you at least) opinion on what she is hearing- you may get some real insight. I know I have.
WAF (Wife Acceptance Factor)and Speakers
How important is the fabric on speakers to their sound? If I changed the covers of my speakers to a more decorative fabric to please my girlfriend, would that really be a big deal? Obviously, I wouldn't cover them with wool blankets, but would, for example, a light silk really sound that much different than whatever the manufacturers use? Given that many audiophiles think that the shape of their AC cords dramatically affect the sound, it is interesting that no one seems to discuss this topic. Any ideas or advice would be greatly appreciated.