Im not gonna lie dude, i haven't had any experience with either of thoise last 2 amps, but, from what i looked up and researched, they both seem to be a decent choice in that price range.
Think about it this way, why is a Mercedes more expensive than a Hyundai? you pay for quality.
After looking up some reviews, and asking around i would go with the Cadence over the Audiopipe, but again, that is just my preference.
Personally, id go with a Kicker or MB quart DSC series amp. But, thats just my choice..