Yeah, I'd probably set up the EQ using 80Hz and let that work just as well for 50Hz. You can adjust all eight EQ's independently for each of the five presets (preset 6 is a bypass, so there's no adjusting it), but you can also just adjust the global (setup) preset and it'll apply to all five presets. Unless you have a case that needs the extra EQ channels below 50Hz, I'd probably adjust the EQ's once with the 80Hz crossover and use those settings all the time, but if you do have a use for the extra EQ channels below 50Hz then you certainly can adjust the EQ's separately for preset 1 and preset 2. Even in that case, though, I'd probably start with the "SETUP" preset and the 80Hz crossover (so that all five presets are optimized for 80Hz) and then do preset 1 with 50Hz.