My rack definitely looks like a throwback to the 70's with all the LP covers strewn about. i like tweaks but often they come & go...the LP covers will stay in place until i'm deaf & done with this hobby!
Michael V, consider that your wood blocks are coupling the component to the shelf below. The Lp covers add a simple layer of isolation which, somehow, is musical to my ears. If your shelves are MDF or glass or stone or anything but real tonewood, the LP covers or some similar material might do good things...its easy enough to test this one out.
If what you discover is that this (& any other tweak) sounds good to you, look into why it happens. I'm a big fan of coupling, but to me, it has to be followed with isolation. Otherwise you are coupling the component directly to a surface that isn't musical...unless of course, your shelf sounds good right from the start. But, if it did, you probably wouldn't have the footers in the 1st place.

I started out with inexpensive wood blocks but quickly graduated to the expensive pointed brass footers from Mapleshade. I don't use them under my CDP (just LP covers there) but underneath all my analog gear they work great...just wish these things didn't cost so much so others would be tempted to experiment.
matt