The MC-60s wil be fine for the SF Auditors. I am running a Dynaco ST-35 (restored and upgraded) into a pair of SF Concertos. I installed a cap in the inputs of the ST-35 so that it doesn't see anything less than 80-HZ, this greatly conserves its power. A REL sub does the low end--Love it! Its not my main system. For that I use a MC-252 and a REL Stadium III.