Ok guys

Have you tried without?

No, I haven’t. Even if taking the dustcover off would somehow result in minor sonic improvements, which I can’t imagine with that particular table, I’d give a higher priority to keeping dust off of the platter (which is made of a material that is not necessarily the easiest to keep clean). And I’d rather not have to take the dustcover off and put it back on before and after listening sessions.

Best regards,
-- Al

Put me in the no dust cover camp, that's +5 and counting. Enjoy the music

A dust cover is a no-brainer to be desired. Nobody wants dust on their records, turntable, tone arm. Nobody wants the acoustic energy in the room vibrating the sensitive cartridge/arm system. The trick is to do it in a way that doesn’t create more problems than it solves.

i guess dust covers are like politics, religion, olives, and Kenny G. All taboo subjects in polite company.

It’s interesting that the pro dust cover guys, so far, are both owners of SOTA turntables. I owned a Star Sapphire Series III with vacuum  for most of the 1990s, and never used the dust cover. Al is correct that the felt platter mat does/did accumulate dust.

Mc,  https://www.sleevecityusa.com/Antistatic-Record-Cleaning-Arm-p/tac-01.htm. If you get one let me know there are a few tricks to setting it up right. 
Guys, as I said before the SOTA sounds better with its dust cover on and down as does the SME. It is like taking the blur out of a photograph. I have done the fore mentioned experiment and I can routine tell when the dust cover is down blind folded. If your turntable sounds worse with the dust cover down then have a platform dust cover made or get a new turntable. Not using a dust cover is not an option. Record safety is paramount. Using a conductive sweep arm will help but still incidental dust will fall on the record not to mention get into your tonearm and bearing.