Kicker Key180.4 plus Hideaway 11HS8
 

I have a Kicker Hideaway and am strongly considering adding the Kicker Key180.4 amp. Is anyone already running this setup? If so, do the power levels of these two work well together? For example, can the sub output keep up with the extra speaker volume produced from the Key amp? Also, where do you have the crossover set for each? Thanks!

What speakers you use with the Key will be a big factor in total loudness. Also, if using the Key, use it in bi-amp mode on the fronts only to get the most out of it.
The Hideaway's built in crossover maxes at 120Hz, so just adjust until it sounds right to your ears. Most people find around 80Hz to be good, depending on your other speaker's capabilities.