Are Dust Covers a MUST

Dust covers not only keep the dust out but also keep wandering hands away. Many of my customers regretted not having a dust cover on when they lost an expensive stylus to cleaning ladies, kids, pets, or even their own loose sweaters.
I don't recommend keeping the dust cover on when playing, however, as its resonance will screw up the sound (the cartridge picks it up).
Disclaimer: I sell dust covers.
Vinh Vu
Gingko Audio

Chasmal et al.:
We mounted a B&K accelerometer on the plinth and/or platter and compare vibration with and without the dust cover while playing different frequencies through the system.
Vibration is much more with the dust cover on. How it translates into better sound depends on your system and your ear. If the listener cannot tell the difference then it should not matter to him/her.
I cannot see how a cover can "block" vibration. Being a hard material, it not only transmits the vibration but also resonates at its own frequency as a result. That should add to the overall vibration, not reduce it.

Ihcho:
We make both plinth top and table top covers. Plinth top sits on the plinth and table top sits on the "table" or rack shelf.
If you don't mind the larger size, table top protects the TT better, and people like the fact that it is like a museum case over their fancy looking TT. Plinth top has the advantage of being smaller, hence easier to handle. The best cover is the one you will use, just like the best camera is the one you will use. I used to own a fancy Nikon, but found that I carry my Panasonic Lumix in my pocket everywhere, and thus using it the most.
So some prefer plinth top, as it is easy to lift and replace.
In any case, take the cover OFF when you play records. The higher resolution your system is capable of, the easier it is to tell the positive effect.

Ihcho:
www.gingkoaudio.com
Vinh Vu