ct(merger, 0, 2);
          aRatePanner.connect(inverter).connect(merger, 0, 2);

          source.start();

          const buffer = await context.startRendering();

          const kData = buffer.getChannelData(0);
          const aData = buffer.getChannelData(1);
          const diff = buffer.getChannelData(2);

          // The difference signal must NOT be constant zero.
          assert_not_constant(diff, `Panner ${param.name} – diff`);

          // Verify that the k‑rate output is constant over 