Yep, I contacted them and they were quickly responsive and suggested a Russound speaker-level to line-level converter and told me it would not affect the performance of the sub in any way. The converter is available through Crutchfield for less than $40.
And yes, other svs subs have speaker-level inputs built in, but the micro3000 does not. I'm liking the micro3000 as my preferred option, if I do decide to step away from my older-but-good Pinnacle. I'll wait to test out the Pinnacle with my new Q Acoustics Concept 50 speakers in my new house, first, though... it might be fine as-is, but I'm exploring my options and it's good to know there is a viable option.