Quote from d08:
Nothing is recoverable in that case, basically once you write over the sectors (or do the so-called LLF) there is no way to recover anything since it's magnetically impossible.
I stand corrected, apparently a company called KUERT Information Management claims to even recover data from overwritten parts of the discs, although this seems to apply to data the user thought was overwritten but is physically intact. I would like to see someone recover anything after overwriting a sector 10 times - there is no need to dip anything into acid.