  Motivated by recent experiments, we analyse the phonon-assisted steady-state
gain of a microwave field driving a double quantum-dot in a resonator. We apply
the results of our companion paper, which derives the complete set of
fourth-order Lindblad dissipators using Keldysh methods, to show that resonator
gain and loss are substantially affected by dephasing-assisted dissipative
processes in the quantum-dot system. These additional processes, which go
beyond recently proposed polaronic theories, are in good quantitative agreement
with experimental observations
