There is much more to consider than just the size of the cone. The magnet structure, the amps power, the equalizer in the sub, and then the room, placement, etc...
Rel subs are some of the best out there and they have smaller cones compared to others, Plus, Rel recommends hooking up the subs so the main speakers run full range and the Rels just add to the lower octaves to the mains.
Personally I prefer multiple smaller cones in a sub instead of just 1 larger cone, same goes for my main speakers. Instead of getting a 15” woofer, I would get multiple 8 or 10” woofers.
Rel subs are some of the best out there and they have smaller cones compared to others, Plus, Rel recommends hooking up the subs so the main speakers run full range and the Rels just add to the lower octaves to the mains.
Personally I prefer multiple smaller cones in a sub instead of just 1 larger cone, same goes for my main speakers. Instead of getting a 15” woofer, I would get multiple 8 or 10” woofers.