Whenever CD Players and Blu-Ray Players experience excessive vibrations, their error correction circuitry kicks in to ensure they can continue to track the disc that is being read properly. When the error correction circuitry kicks in, the dynamic range is limited, sound quality is compromised, and you are restricting the performance of your blu-ray player. My Pioneer Elite BD-09 address this by using heavy duty composite material feet with an additional absorptive, spongy layer to help reduce vibrations.
I have tried several different feet, and the best are made by Harmonic Resolution Systems - one spacer and two couplers make "one isolation foot" and you need 3 of these sets per component. They make a remarkable difference! Audioquest, Herbie, the old "Mod Squad," and several other companies make various versions of these, but HRS really knows what they are doing. Mod Squad was the first company to make a "footer" and they made a great one - it featured a soft sorbothane footer that vibrations which you could use alone, but you could also insert a 1/2" Tip Toe (the first isolation cone) into the rim of this footer. The combination of an aluminum cone and a sorbathane footer was very effective, and every so often, you can find them on the used market (I still have a bunch of them).
If you have a "normal" rack that is not made by Harmonic Resolution Systems or some other company that specializes in isolating the shelves from vibration (these racks are expensive - over $1,000), then it is definitely worth your time and money to invest in isolation feet for your Blu-Ray Player and your CD Player.
Good Luck,
Dave