In a slightly different context than the OP, I went from Martin Logan Odysseys to the Spatial X3’s, with a brief Ohm Walsh 2000 stop in-between. The Ohm’s are nice, especially for the price. In terms of the X3’s efficiency, and my listening room is fairly small, I use a Graaf GM 20 OTL to drive them and it does so to much higher levels than I can stand for extended periods of time, and sounds great great in the process. I switched from the Logans as space was a consideration (from the room in our last house), not because I didn’t like the speakers. That said, I like these Spatials very much, they work perfect for my space and sound great.