I use the Oreas under my integrated and SACD player and will never take them out. They made a noticeable improvement. And like twoleftears said, heed the recommendations on the weight limits.
To try them out, I ordered one set that just met the upper limits of the weight allowance and the next size up that easily accommodated them. The next size up worked the best, for me. It worked out to something in the 40-70% weight limit that did the trick.
All the best,
Nonoise