  Within a random matrix theory approach, we obtain spectral statistics of the
Wigner time delay matrix $Q$, for arbitrary channels number $M$ and for all
symmetry classes, in fact for general Dyson parameter $\beta$. We also put
forth two conjectures: one is related to the large-$M$ expansion of joint
cumulants of traces of powers of $Q$, which generalizes and implies a previous
conjecture of Cunden, Mezzadri, Vivo and Simm; the other concerns the tail of
the distribution of traces of powers of $Q$.
