  We study the density of states (DOS) for disordered systems whose spectral
statistics can be described by a Gaussian ensemble of almost diagonal Hermitian
random matrices. The matrices have independent random entries $ H_{i \geq j}
  $ with small off-diagonal elements: $ <|H_{i \neq j}|^{2} > \ll <|H_{ii}|^{2}
> \sim 1 $. Using the recently suggested method of a {\it virial expansion in
the number of interacting energy levels} (Journ.Phys.A {\bf 36}, 8265), we
calculate the leading correction to the Poissonian DOS in the cases of the
Gaussian Orthogonal and Unitary Ensembles. We apply the general formula to the
critical power-law banded random matrices and the unitary
Moshe-Neuberger-Shapiro model and compare DOS of these models.
