I’ll probably get yelled at for this, but I had the LFT-8b in a small room (10’x20’) a few years ago. It was powered by a Luxman MQ-70, a rare 35x2 EL-34 tube amp influenced by Tim de Paravicini. Well, it rocked without clipping and distorting, easily into the 90db’s, maybe even 100db peaks. This was also considering sitting about 7-8’ away. One thing to consider is the added gain from a preamp, which is likely 8-14db, and room gain. Once you add all that up, it boils down to the quality of the current and of each watt.
Given the OP’s room size, a more powerful amp might be needed, but perhaps not necessarily.