Don’t worry about overkill for your room, you need it. You definitely want something like the dual Empires for the best, visceral, HT experience. The powered woofs in the LSi 15s won’t cut it alone. As Alex said, the 14 ga. is fine. To power the setup, a Denon 3310 & Emotiva XPA-3 combo can be had for around $1,400.