  We introduce a method for the verification of nonclassical light which is
independent of the complex interaction between the generated light and the
material of the detectors. This is accomplished by means of a multiplexing
arrangement. Its theoretical description yields that the coincidence statistics
of this measurement layout is a mixture of multinomial distributions for any
classical light field and any type of detector. This allows us to formulate
bounds on the statistical properties of classical states. We apply our directly
accessible method to heralded multiphoton states which are detected with a
single multiplexing step only and two detectors, which are in our work
superconducting transition-edge sensors. The nonclassicality of the generated
light is verified and characterized through the violation of the classical
bounds without the need for characterizing the used detectors.
