Did I reply you on Gearslutz as well?
Just in case copying my text here.
I am not an expert myself but I think this cable might do the trick. I would check the Tascam manual anyway. I would set the BNC Out 1 to "timecode" instead of "AES3id". I think "timecode" is the audio encoded SMPTE which the MixPre will recognize. (HS-P82 User Manual, page 42).
https://www.bhphotovideo.com/c/product/751718-REG/Remote_Audio_CATCIPBNC_BNC_to_1_8_3_5mm.htmlWhat I _do_ know is: that timecode input is SMPTE LTC, which encodes a clock signal that offers a timestamp (HH:MM.SS.ff where ff is frame number). That timestamp is used by the recorder to timestamp the start of the BWF files.
So, when you import those timestampted BWF files in a timecode capable audio/video editor it will know how to align them.
However: it's not a wordclock, which means that the clocks of the A/D converters won't be synchronized. The drift and jitter of two high quality clocks should be really minimal anyway. But I would do a test before doing some real work.
Depending on how you configure the timecode you can also use it as a trigger to start recording on the MixPre. So pressing record on the Tascam should start feeding timecode to the MixPre and make it start (you need to configure it, check the manual).
SMPTE timecode is accurate enough to sync audio to picture, but different audio files might have some phasing issues. At worst you will need some tweaking (adding a minimum delay to the files of one of the recorders).