Turntable lid up or off?


My Pro-Ject Classic turntable came with a dust cover.  I usually spin vinyl with the cover completely removed and never closed.  Does it matter if the cover is just up or fully removed?  The ultimate test is just listening, but I cannot detect a difference between either mode (up or completely off).
128x128socalml528
Off

I had a Pro-Ject, and always took it off. Easy to do.

My SOTA has no connected dust cover. I purchased a fitted fabric cover for it when not in use.
Off. It will sound more open.
Up will act as an acoustic pickup transmitting vibrations to the table. 
Off. It will sound more open.
Down it will sound closed in. Removed and placed on end it will be balanced. On the short end of course for greater extension. DO NOT lean against the wall, this will be tilted up. The most stable will be horizontal, but then it will be flat. Lifeless.  

What dust cover cleaning solution are you using?

Socalm, this is an ongoing argument. Lay instinct says you never want to play your turntable with the dust cover closed. Then they say things like "it will sound closed in" Brilliant deductive reasoning.
As far as record care goes you never want to leave them exposed to the open environment for a prolonged period of time. Records are dust magnets. Static electricity will pull dust deep into the groove were the stylus can grind it into the vinyl, the record becomes noisier over time.
As far as sound goes, in a turntable like yours were the dust cover sits right on the same chassis as the bearing and tonearm it is possible that the cover might transmit a resonance that can be heard. In your case you do not hear a difference so it becomes a very easy choice. Now, with turntables that have an isolated chassis which the dustcover does not touch the turntable will sound better with the dust cover closed. The reason is air also transmits vibration. Putting the dust cover down is like slipping on hearing protection. It is so effective Mark Dohmann is working on an isolated dust cover for his Helix turntables.

Then they say things like "it will sound closed in" Brilliant deductive reasoning.
Or, they’ve listened and came to that conclusion. OP, try it yourself. Turn it up. Play a track you know well with the cover down, off, and down again. 
I keep it down when listening to my SL-1200 MK2. Most of my other tables don't have dust covers. Up seems like the worst option. What sounds best to you? 
@millercarbon, I just use a soft micro fiber cloth for cleaning.  My "habit" is to take the cover off and set it upside on a table on the other side of the room (sometimes I just set it on the carpet).  If I'm not using it for more than a day or so, I put the cover back on.  I'm good with a gummy or two.

@all, thanks for insights & opinions.
I must admit to being interested in the answer. I never put the dust cover on my TT... currently a Linn LP12. I always thought they would vibrate and that would not be good. So I did a search and quick survey of the literature, virtually every discussion is like this one with 80% spitballing... “this makes sense, or “do your own thing”. Most manufacturers don’t say anything a few do. I would like to hear something from The Absolute Sound or Stereophile. i didn’t find anything right off the bat. I’ll have another look sometime. I have spent thousands of hours comparing cables and components, things that make big differences. Apparently this isn’t’ one of them. At this stage of my life, I think would prefer to enjoy the music versus doing a critical comparison (I was a scientist, so it would take time and effort). I’m going to keep mine off. My records are pristine, and if I see a bit of dust I use Last All Purpose Cleaner and it’s gone.
The ultimate test is just listening, but I cannot detect a difference between either mode (up or completely off).
There you go.

G
I have always taken the cover off.  The rationale is to avoid vibration when closing it or worse case scenario the cover slamming down.
My forced air hvac system creates a LOT of dust, I could never leave a dust cover off when not in use.

UP, to avoid ’trapping’ and ’reflecting’ micro vibrations.

OFF, if possible, for appearance, at least for long listening sessions, I guess I would simply leave the hinged type up for single play, like I used to do with an Audio Technica I had.

In my case, the cover on the big JVC plinth is large, heavy, unattached, it must be removed. Luckily it has notches on the sides to get a good grip on it. And bimps on the plinth to align the front first, then lower without hitting anything. Very important in my situation, I have very small clearances: height and sides of 2 of my 3 arms I squeezed in there.

Notches are an advantage: not needing to reposition your hands. Off, down, lean vertically to defy gravity, back up to TT, no need to walk anywhere.

I put felt pads on the edge resting on the floor, to keep from scuffing it to hell and back, resist sliding, and isolation from floor vibrations.
When I got my SL1200G turntable, I listened both ways, with the cover open or closed using the same record.  After about 10 try’s, I found the open position better and go with that now. 
Seems a lot of higher end decks don’t come with covers so my guess is it doesn’t make a difference or better to be off. Great to keep dust off is probably all it does.
HhahahahahahaA difference in sound with the dust cover closed or removed.
SNAKE OIL!

    There is no difference.

 I have 2 SL-1200 mk2’s
one SL-1210. 
 No difference.    Just play your LP’s’ and enjoy. 
Had first SL-1200 mk2 for 30+ years. 2nd one about 5 years later.
then the SL-1210 in mid late 90’s if I remember correctly. 
    All with ortofon Arkiv and Ortofon nightclub II CONCORDE stylus.   All flawless, and no hiccups, no be,ts to tinker with.
all sound amazing.  With lid down or up,

 I can hear the cymbal and hear the drum stick hit the cymbal with the cover up, .......yeah ok....
  oh wait,....the cymbal decay is more prevalent with the cover removed as with the cover down??
ok, sure you can. 
 Just play your albums and enjoy.
don’t follow this snake oil tripe. 
VPI Classic 2  gives me  few options.  It is either on, in place, or completely off.  It is not hinged or fastened  but sits in place held by its weight. I almost always take it off.  Sometimes leave it on when rambunctious kids or dogs are visiting. 

BTW, as dust covers go, it looks OK, but has some curiously placed open spaces, like screen doors on a U-boat.  Better than nothing, but could be a tighter fit. 
I ordered a custom dust cover for my table....heard a reduction of fidelity....too big for a hinge.   Off or on.....I sold it a month later.