Exemplary apparatus and associated methods involve a bypass module for modulating conductivity of one or more current paths to provide a first set of LEDs that are conducting near minimum output illumination and having a larger conduction angle than that of a second set of LEDs that conduct at a maximum output illumination. In an illustrative example, the conductivity of a bypass path in parallel with a portion of the second set of LEDs may be reduced while the AC input excitation is above a predetermined threshold voltage or current. The bypass path may be operated to provide a reduced effective turn-on voltage while the input excitation is below the predetermined threshold. For a given maximum output illumination at a maximum input excitation, the bypass module may control current through selected LEDs to construct an input current waveform with substantially improved power factor and reduced harmonic distortion.