  Quantum dots have sharply defined energy levels, which can be used for high
resolution energy spectroscopy when integrated in tunneling circuitry. Here we
report dot-assisted spectroscopy measurements of the superconductor $NbSe_2$,
using a van der Waals device consisting of a vertical stack of
$graphene-MoS_2-NbSe_2$. The $MoS_2$ tunnel barriers host naturally occurring
defects which function as quantum dots, allowing transport via resonant
tunneling. The dot energies are tuned by an electric field exerted by a
back-gate, which penetrates the graphene source electrode. Scanning the dot
potential across the superconductor Fermi energy, we reproduce the $NbSe_2$
density of states which exhibits a well-resolved two-gap spectrum.
Surprisingly, we find that the dot-assisted current is dominated by the lower
energy feature of the two $NbSe_2$ gaps, possibly due to a selection rule which
favors coupling between the dots and the orbitals which exhibit this gap.
