Has it been stated that the CVR cannot provide additional information? As I read the release from the NTSB issued on 7th March it suggests that with filtering it may be possible to determine more elements of FD communications and environmental noise. Today's information offered by 9gmax, although I can't see it on the NTSB website, seems only to include ATC communications which are likely to have come from ground recordings. The earlier release talks about crew communications being consistent with a loss control of the aircraft....but this is not really consistent with FD actions. As with the ET accident, I find the wording of the information that is being issued by key agencies to be interesting - the text from NTSB refers to 'engines increased to maximum thrust', but does not mention TL movement. But, perhaps I am reading too much into this.
Hopefully there is enough information available or ultimately accessible to enable some of the present questions to be answered.