I have Deftechs and the problem with DT's is their stated settings are not always the best. If they say to set the Mythos 2 to 100Hz then I would (considering the mythos track record) but I will say that my mythos gems DT recommneds 120Hz yet Audyssey sets them to 150Hz which is more truthful.
The Mythos 2 can be set to 100hz and I would set the subs crossover to 100hz, 80hz is not a set in stone number and I doubt you will hear "voices" coming thorugh the sub at 100Hz (120 and higher yes, but 100 doubtful) so you should be safe.
Basically the Mythos will start to drop off at around 120hz but you will still get usable sound at around 100hz and your sub will pick up from there. We are talking about mid bass sound so will you notice it, nah I don't think so. But you should be safe at setting the sub at 100hz, if it's too much go back to 80hz and you will only be missing 20hz on the frequency scale, so not much.
