Kr4 - If the speaker was designed and voiced with the grille cloth on, then it will only be able to perform as intended with the grille cloth on.
Indeed. Example Harbeth - grills on.
Indeed. Example Harbeth - grills on.
Grilles or No Grilles
I've always found that 'no grilles' leads to a more accurate listening experience. I've had many different speakers using many different grille cloth and components and always, no grilles works better for me. Often many of my friends find that a WAF means grilles on. What do you think?