The Constitution says, "This Constitution, and the laws of the United States which shall be made in pursuance thereof ... shall be the supreme law of the land ...".
I have no quarrel with that. In areas delegated to the federal government by the Constitution, federal laws prevail as long as they are consistent with the Constitution. In the areas reserved to the states by the Constitution (everything not delegated to the central government), state laws prevail so long as they don't violate the Constitution.
Precisely. Just the same, Amendment 10 is part of the Constitution and, per the supremacy clause, takes precedence over all laws including federal ones that are violative of the powers reserved to the states by that amendment. As a result, state laws enacted under Amendment 10 are indeed supreme to federal laws that violate Amendment 10 because Amendment 10, as part of the Constitution, is supreme to any federal law.