  The `fundamental plane of black hole accretion' (FP), a relation between the
radio luminosities ($L_R$), X-ray luminosities ($L_X$), and masses ($M_{BH}$)
of hard/quiescent state black hole binaries and low-luminosity active galactic
nuclei, suggests some aspects of black hole accretion may be scale invariant.
However, key questions still exist concerning the relationship between the
inflow/outflow behaviour in the `classic' hard state and quiescence, which may
impact this scaling. We show that the broadband spectra of A0620-00
and~\sgra~(the least luminous stellar mass/supermassive black holes on the FP)
can be modelled simultaneously with a physically-motivated outflow-dominated
model where the jet power and all distances are scaled by the black hole mass.
We find we can explain the data of both A0620-00 and~\sgra~(in its non-thermal
flaring state) in the context of two outflow-model scenarios: (1) a
synchrotron-self-Compton dominated state in which the jet plasma reaches highly
sub-equipartition conditions (for the magnetic field with respect to that of
the radiating particles), and (2) a synchrotron dominated state in the
fast-cooling regime in which particle acceleration occurs within the inner few
gravitational radii of the black hole and plasma is close to equipartition. We
show that it may be possible to further discriminate between models (1) and (2)
through future monitoring of its submm/IR/X-ray emission, in particular via
time lags between the variable emission in these bands.
