If the LFE crossover is at 80 and my speakers are crossed over higher than that, am I losing sound between them?
The LFE crossover only affects the low frequency effects channel (the .1) of a 5.1/6.1/7.1 soundtrack, not overall response from redirected bass. The 705 defaults to the THX LFE cutoff of 80Hz and Audyssey doesn't adjust that setting. However, the LFE channel by its very nature is brickwall filtered during encoding at 120Hz. If you want to accurately reproduce the entire LFE channel, set LFE cutoff to 120Hz. However, few sound mixes have audio above 80Hz in the LFE channel, which is why THX recommends the 80Hz cutoff. Also, because the LFE channel receives a +10dB boost during decoding, the THX recommended 80Hz cutoff is there to reduce the chance of humming/noise above 80Hz from the LFE channel. Chances are that you will not notice a significant difference, if any, by changing LFE cutoff from its default of 80Hz, but doing so has no effect on the bass redirected from the other channels.