AQ sky also has CARBON-BASED 5-LAYER NOISE-DISSIPATION SYSTEM Cheetah does not.
I had a pair of Sky that Cable Company lent me. I have very revealing equipment but I couldn't hear the difference between the 2. Here's what you get going from 36v Cheetah to Sky (Everything else is identical): 72v dbs, slightly different xlr connectors and 50% more air.