It has been years since they used tape recorders. Everything is digital nowadays. I agree that it is somewhat unlikely that they survived impact but I don't believe it is impossible. Their value would be in recording the last voice communications amongst the crew -- clues to the mishap might reside in those comments and possibly some thoughts that might provide the families with last thoughts. I know there was controversy on another thread about the existence of such recorded conversations from Challenger but I am here to say that they exist and were never made public by official fiat.
As I recall, the transcript had comments that the family wanted with held due to their content.
Also, don't you think it's unlikely any meaningful conversations took place giving the rapid break up?