Grilles or No Grilles

The foam grills like the ones JBL used years ago were suppose to be the most transparent; you could probably make some [or have them made] if the appearence appealed to you. Many speakers now are designed to look good nude, with the front finished to match the rest of the speaker.

My Frazier Concertos had similar foam grills. They were the closest to acoustically transparent as you will find.

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My Infity Kappa 9 sound just fine with the grilles on and I could not not detect any difference with the grilles removed, so I leave the grilles on them all the time. However my Infinity IRS Betas have always been played naked. Every display that I've ever seen show the Betas without grilles. I think I put the grilles on them once just to see what it looked like....no dice, naked is the only way to fly with the Betas.
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The grills on my Egglestons were very transparent - both aesthetically and sonically. I heard no difference. It was a very elegant design (super thin, sheer) and I could actually still see the drivers when the grill were on, so I kept them on. My new speakers don't come with grills.

Gentlemen,
Vandersteen speakers not only sound better with grills they measure better. Any one who thinks they can hear a very sheer double knit grill double blind is most likely hearing the diffraction caused by improper grill frame design. Many of the worlds most expensive tweeters use wire mesh or fabric for protection without sonic effect.
Thanks Johnnyr