The shims are wafer thin and fit between the metal feet and the case cover. Therefore, to fit you need to unbolt the foot or feet that require shimming.
Make sure that when placed on the surface the feet are absolutely square with no rocking at all. Tapping each corner will show you if there’s any play. Even the tiniest bit of play will impair performance.
I could do with some for my CDS3. One foot is out. I have shimmed it with super fine washers but would like to see what the naim ones are like. Did you buy direct from them?
Peder, it’s a good question. AFAIK, no, mainly because there’s no real compliance, so fully done up, is fully done up. Try to overtighten beyond the point of most resistance and all you do is risk stripping the thread.