I have a home made sub encloser with two 12" infinity woofers. They are 4 ohm rated. I was running them with a 2 channel adcom amp for years. After receiving my 990/7700 combo I decided to try using 2 of the 7700 amps channels to drive the subs. It works well and sounds better then the adcom did. More power from the outlaw amp. The 2 amp channels driving the subs do tend to get hot, but it has not shut down. The only thing I don't like is not having a dedicated sub crossover level control in the 990. My center crossover is the highest at 100htz, so I assume thats also my sub crossover?