even an spl sub on the same amp won't be that much louder to the ear than a w7, if at all. you could put 6 different subs on that same amp, and as long they are all in a well designed box, your ear wouldn't be able to tell much of a difference in terms of spl. the only way it will change significantly is by adding cone area or power. 2 250 watt 15's will obviously be louder than 1 500 watt 12, but that's apples to oranges. what i would say though, is that i hate to underpower a sub. the only way i will do that is to plan for that in the box build, and give it a little extra volume, which i also hate doing. point being, the W7 will sound just as loud to the ear as any other sub of the same power. metering for spl is another ball game.