Mass and vibration cancelling on top of CD player?

Geoffkait,
How would you check it then? I'm only asking out of curiosity, because I don't really think that it matters that much with my type of transport as ong as it isn't really off.

Generally speaking then, the level should be placed directly on the spindle or another place on the transport compartment that is the same level as the spinning CD. Using the top of the CD player chassis or even the CD tray is unreliable. Unfortunately, unless the player is a top loader the cover of the player must be removed to gain access to the transport compartment. The reason level is critical is that a spinning CD will flutter more if not level, especially when out if round as many are.

But not if it's clamped; and that is why the Pioneer stable platter design was so good.

Maybe so, Roxy54. I'm speaking generally. The laser is suspended on springs, so level could be an issue for the Pioneer. Only one way to find out.

The cd tray in mine is a machined aluminum platter with a removeable rubber mat, which is the point of contact with the CD. How could that be unreliable?