I have also seen this kind of corrosion. I believe it's caused by moisture retention in the cabinets, I'd suggest drying them out with the drive units removed. I'd not use anything oil based on the drivers, it can affect adhesives, just a clean/rub-down of affected areas and a thin brush painted coat of matt acrylic clear lacquer, that should help. Treating the cabinet exteriors with light Danish Oil may help reduce absorption of atmospheric moisture.
It is impossible for anything digital to sound analogue, because it isn't analogue!