  We study the non-equilibrium linear response of quantum elastic systems
pinned by quenched disorder with Schwinger-Keldysh real-time techniques
complemented by a mean-field variational approach. We find (i) a
quasi-equilibrium regime in which the analytic continuation from the
imaginary-time replica results holds provided the marginality condition is
enforced; (ii) an aging regime. The conductivity and compressibility are
computed. The latter is found to cross over from its dynamic to static value on
a scale set by the waiting time after a quench, an effect which can be probed
in experiments in {\it e.g.} Wigner glasses.
