Are Dust Covers a MUST

Concur with Vtvu. Having a dust cover is probably going to make the system sound worse. ime, I tried using Cardas RCA covers and they noticeably imparted a metallic signature to cymbals that was not there when they were removed. The only issue was that they decreased the noise floor significantly so I went looking for replacements. I've recently picked up the Acoustic Revive units which I hope won't have the same drawbacks but will have the noise floor benefits.