For $1000 the JL HD900/5 puts out 500wrms to the sub at 1.5-4ohms.
For $750 the Alpine PDX-V9 puts out 500wrms to the sub at 2 and 4 ohms
It might be difficult to find a 5 channel that puts out 500wrms. What's the reason you need a 5 channel? It makes it hard to upgrade substage and speakers separately later.
space and simplicity, I have two rockford powers right now great amps, but it takes up too much space. I really could use a 4 channel if it had a subsonic on it, Im only running comps and subs