They absolutely do not do the same thing. One is an auto eq/signal summing device that corrects factory eq, timing, and polarity (will NOT correct or counteract all pass filters). The other is a MOST150 preamp that takes the digital signal on the MOST150 fiber loop and converts it to a format that is usable by us.
Why are you jumping down my throat....... Overall, they do most of same things.... just different technological methods. Both are cleaning up factory EQ settings, Both clean up factory Timing settings, both supplying a clean flat signal to be used for an Amp and/or DSP. The Nav-tv is more advanced and does a better job to get that good clean signal (yeah, by removing AllPass) So, on a Basic level, they both produce almost the same results......at least similiar results that would apply to the OP original situation.