The M80s are only down 3 dB at 34 Hz. It takes a pretty large sub to get substantial output below that. But if you're looking for the kick that you feel in your chest cavity, that's several octaves up from there. The M80s handle that range very well. But it's easy for their position in the room, and your location too, will hide much of that bass energy.
Honestly, you don't seem to listen to people's advice, so you'll probably go and do your own thing. But you really should try moving the speakers around the room to see if you find that bass you're wanting, before investing any more money.
