Manual Prop for TT cover

The other side of the coin is lowered dust cover reflects vibrations emanating from the cartridge back at the cartridge thus enhancing a resonance that interferes with transduction. Listen both ways and decide for yourself. But when you do that experiment, remove the dust cover completely.

Yes, remove it from its hinges so you can then remove it completely when you actually play LPs.  You can put it back in place when the TT is not in use. I have never met a dust cover that did not detract from sonics if lowered during LP play.  Most audiophiles agree; some do not.