  Identified particle observables from viscous hydrodynamics are sensitive to
the fluid-to-particle conversion. Instead of the commonly assumed "democratic"
Grad ansatz for phase space corrections $\delta f$, we utilize corrections
calculated from linearized covariant transport theory. Estimates based on a
pion-proton system with binary collisions indicate that protons are much closer
to equilibrium than pions, significantly affecting the dissipative reduction of
differential elliptic flow in Au+Au at RHIC. In addition, we test linear
response against fully nonlinear transport for a two-component massless system
in a Bjorken scenario. Strikingly, we find that, while linear response accounts
well for the dynamical sharing of shear stress, the momentum dependence of
phase space corrections is best described by Grad's quadratic ansatz, and not
the linear response solution.
