What they said...
While I don't have direct knowledge of using a Mainline for speakers, I can attest to what similar speakers need as far as power. I have a small (135 sg. ft.) enclosed office and the SEX amp, augmented by a powered sub, drives very similar speakers in the near-field. At normal office listening levels, where a conversation can still take place, the amp is running at about 70% on the volume control. At volume settings down around half, dynamics start to suffer as do perceived extensions. While volume settings are not the whole story, it tells me that the speakers might deliver even more with more power on tap. My 2C, YMMV and as Doc said, it won't hurt to try.