FlyteBand, the video link below is how line 6 recommends connecting Helix to Mixer. It is how I run my Helix LT to my Zoom Livetrak 12 mixer, and then out to my P.A. This site does a good job of defining , mic level, line level, instrument level, etc. It explains that the MIC level is a lower "loudness" or "strength" than the LINE level. Hope this helps.
http://www.ovnilab.com/articles/linelevel.shtml