If we can cut wages ~£5m a year from what they have been, or better yet get down to the amounts clubs like Coventry and Luton have been spending, and make constant big player sales (minimum one Downes every season) then that puts us into vaguely sustainable territory. The £20m deficit we ran in Martin's first season is obviously an impossible task to cover year on year with new investment. "Backing the manager" with outrageously expensive loans like Christie/Wolf/Grant does the club no good at all.
Realistically clubs at this level can only run sustainably if they're a tight ship with a small squad (backed by a good academy), and have a manager who is happy to work under those conditions. New investment clears the debts and gives the club some cashflow to work with, but unless much more is to come then spending has to be reined in. Speculate only after accumulating from the last speculation (Piroe, maybe Wood).