  The search for empirical schemes to evidence the nonclassicality of large
masses is a central quest of current research. However, practical schemes to
witness the irreducible quantumness of an arbitrarily large mass are still
lacking. To this end, we incorporate crucial modifications to the standard
tools for probing the quantum violation of the pivotal classical notion of
macrorealism (MR): while usual tests use the same measurement arrangement at
successive times, here we use two different measurement arrangements. This
yields a striking result: a mass-independent violation of MR is possible for
harmonic oscillator systems. In fact, our adaptation enables probing quantum
violations for literally any mass, momentum, and frequency. Moreover,
coarse-grained position measurements at an accuracy much worse than the
standard quantum limit, as well as knowing the relevant parameters only to this
precision, without requiring them to be tuned, suffice for our proposal. These
should drastically simplify the experimental effort in testing the
nonclassicality of massive objects ranging from atomic ions to macroscopic
mirrors in LIGO.
