However, if the pickaxe does not have silk touch, I only want to drop block XYZ without the random drop.

If a player (single or multiplayer) breaks block XYZ with a pickaxe that HAS silk touch, then they get that same block PLUS a random drop. Hi - sorry to add on to such an old post, but using 1.8.1, I'm trying to do something similar but I think the logic is reverse to what the Affected by Silk Touch box has.