Yep.
"A major innovation in constitutional law was the development of a requirement that election districts in each state be structured so that each elected representative represents substantially equal populations. Although this requirement has generally been gleaned from the Equal Protection Clause of the Fourteenth Amendment,1 in Wesberry v. Sanders,2 the Court held that construed in its historical context, the command of Art. I, § 2, that Representatives be chosen ‘by the People of the several States’ means that as nearly as is practicable one man’s vote in a congressional election is to be worth as much as another’s."
Districts = the people directly vote for the person representing them
This negates the possibility of proportional representation w/o an amendment.