I'm coming out with a trick in another month, and want to credit the card control that I recommend. It retains the top stock (about six cards). I believe it's quite old, but don't know the provenance.
Begin with the cards face-down in your right hand. Spread the cards a bit so that the bottom of the stack fans casually to the left.
Keep your eye on the back of the last card in the stack (it is marked on the back with a pencil dot). That represents the beginning of the stack of force cards, whose order should not be disturbed.
Lift the cards so that the faces are toward the audience. Sloppily pull a few cards free of the deck with the left hand. Place those cards behind the stack, keeping your thumb firmly in place over the force cards. At the same time, with your right fingers, push a card or two to the left-hand group.
Pull the left hand away from the stack again. Immediately place the left-hand stack in front of the right-hand stack, pushing a card or two over with the thumb. Leave that card or two in the right-hand stack and once again move your left hand to the left.
Now repeat this procedure. This is the control.