How do i level speaker stands.

I have purchased a pair of monitor speakers; Reference 3A MM De CAPO. Haven't purchased stands let. When planing set up I found that the flooring is not level. Using a piece of weighted plywood (approximate foot print of speaker stands) and a bubble level, I will need to be able to raise or lower all four corners by as much as 1" (in reference to other speaker so both would be at the same height). Should i do this with just the stands or with a leveled platform that the stand will set on? It seems most of the spikes on stands don't have that much adjustment or if extented that far appear unstable.
Flooring is in an upper floor apartment. Its some kind of lightweight concrete poured over wood subfloor; 3/8" pad and carpet ontop?
Ot