the actual output of the 1000/1 is closer to 1400wRMS. the thing to consider is if you need the 1 ohm stability of the JBL or of JL'2 1.5 ohm rating is enough, and keep in mine at 4 ohms, the JBL is 600wRMS. The JL at 4 ohms is still a full "1000 watts" however with two subs, that's ~500+wRMS per sub.. the JL will divide power between subs in parallel. The JBL will double its output when going from 4 to 2 ohms. It's a matter of matching the amp's output to the subs you'll be using.