You can easily repackage/optimize your archives with our software - check my signature.
KCC was create mostly for Kindles but I know people who use it with other readers. I never used Aura HD but let me share probably the best settings - Aura HD users feel free to correct me. I would love to add Aura HD settings to our wiki.
http://aw.cap.vulturis.eu/2013-11-13_0803.png