  We revisit the problem of determining the real-frequency density response in
quantum fluids via analytical continuation of imaginary-time quantum Monte
Carlo data. We demonstrate that the average spectrum method (ASM) is capable of
revealing resolved modes in the dynamic structure factor of both
ortho-deuterium and liquid para-hydrogen, in agreement with experiments and
quantum mode-coupling theories, while the maximum entropy approach yields only
a smooth unimodal spectrum. Outstanding issues are discussed. Our work provides
the first application of the ASM method in realistic off-lattice systems.
