Does surface a component sit on affect the sound.

I have my components in a wooden wall unit open front to back. Would I be wise to get something soft between a unit's feet and the shelf to improve the sound. House is on a slab and the wall unit is on the bottom floor resting on a carpet which is directly on the slab?

Yes, it will affect the sound.

What you use to sit it on is a matter of great debate.

Points, cones, spikes, tennis balls, air bladders, super balls cut in half, styrofoam, sorbothane, roller bearings, etc, etc, are all used by people trying to make their stuff sound better.

You'll never get a consensus here, on this matter(except that it makes a difference, not on what to use).
I thought cables were the abyss of audio, but its component vibration management. I like to post this link to a Stereophile article as guide through the mud.
Hi Eagle: Tom Lyon is an authority on this subject if anyone is... As I recall, Mr. TWL has done mega experimenting with racks, shelving, & platforms. I've tried to emulate some of his sage advice & have come to realize that *everything* affects the sound of a detailed/revealing rig. There are no absolute solutions in that regard; you must experiment with your own combination of components, shelving & rack in order to find what works best for you. Rigid coupling of your rack to the concrete floor via spikes would be a good beginning; the carpet certainly isn't doing you any favors.
One particularly frustrating lesson for me: I had finally found some reasonably good-sounding combinations of shelving & footers (different optimum combo's for each component) then I decided to get a larger rack. Replacing the rack itself changed the whole character of the rig, then I had to begin my tuning experiments all over again.
Thanks Bob, for your kind words.

That is a very nice compliment, coming from someone as knowledgable and experienced as you are.

As most of us know, I use the energy transfer(specifically engineered direct rigid coupling) method with Audiopoints and Sistrum Platforms on my system, and also work for the company which makes these products(and others).

I like the results which consist of removing the unwanted vibrations from the system, but leaving the full dynamic range, and tonal and harmonic characteristics of the music, intact and un-deadened.

I have used TWL's products with great success. I find cones/spikes are more effective than pads/soft polymers. Wood sounds different than metal, or MDF. It's all soo complicated!!! When does the merry-go-round stop so I can get off, I'm dizzy!
Applications of resonance transfer are now being applied within speaker enclosures, speaker crossovers, amplifier chassis design and the source itself, acoustic instruments. Tom