Dust cover up or down?

People spend tons of money to reduce any adverse effects on their turntable caused by vibrations. Removing the dust cover while playing a record is probably the cheapest way to reduce microphonic vibrations that will cause distortion in sound. Some cheap turntables with cheap cartridges may not make much difference with or without a dustcover because the sound is already pretty bad, but very revealing high quality cartridges may suffer from such vibration especially when you listen to music loud with the dustcover up. The dust cover will pick up the sound wave, however small, which may well cause vibration.

There are no absolutes. It totally depends on the turntable in use. Use your ears.

Don’t have, and don’t use a dust cover. 
 

Will likely get one made for my TT to keep the dust off when not in use, but seeing as how it is used daily, it will be spending the bulk of its time stored near by. 
 

Suspect if I get  one made, it will be used if I go away for an extended time.

A friend of mine leaves his on all the time, which is easy as it is hinged. Opens it, puts a record on, closes it. 
 

Seems to me, as the price of a TT goes up, the presence of a cover becomes a rare thing indeed. Especially one that is hinged. Can’t think of a single ultra high end TT that has a hinged cover? Would love to know if there are any?

Dust cover off . It states it in the manual for my tt. 

I have a Sota Comet I bought used and the dust cover is more or less an afterthought, and looks like it, something they started making because there was a demand for it. There are holes for hinges in the back of the plinth, but it's clearly never had hinges on it. I take the cover off and set it aside while playing records.