120 dB at 40hz for playback ? That makes my head hurt...
If we assume 20dB sub haystack - that's 100dB full range. For live music, that's only 5dB more than I'm used to. If that's the peak number the system needs to reproduce, knowing the average continuous will be lower - that's realistic and what I would expect my personal fun system to handle.
If it were me though, I'd get TH118XL's and SH69HT's and call it a day. Get the Dante version DNA amp, and use whatever computers and other devices for sources.