the speakers don't NEED 100 watts. in fact you'd likely find it unbearable tl ositen at 100 watt levels constantly. Not entirely sure in this space, but in musical instrument speaker land it's generally accepted that speaker ratings are thermal ratings- - the speaker will self destruct from the heat if assaulted constantly with that level of power over a significant period of time. It's also the general rule of thumb, at least for bass amps, that you'll start getting compression (speaker doesn't get as much louder as the incoming signal) and distortion around half the thermal rating.
Bottom line is if an 80 watt device won't get what you want out of the speakers, a 100 watt device, only about one dB louder, won't either . . . .