I have more work to do, but so far I have to say the XCON is a low end beast! I built a sealed enclosure that is 1.25 cubes and have a temp amp right now which is a RF 500.1. I have some fine tuning to do, but right off the bat, I know I will be happy with this sub. Played a couple tracks from Bass 305, some Decaf, and some Lamb of God. The presence of the sub is amazing! Completely transparent and I cannot tell where the sound is coming from most of the time, which is due to the setting I have the crossover at currently. I have the crossover set a little high right now, right around 80hz. I'll start to dial it back after I mess with my comps a bit. I haven't had a sub in a long time, so my comps have been running without the crossover active. So it will take a little time to get the system to blend. I think even with 500 watts most people would be perfectly happy with the output. I'm not quite sure if it is the amp or the sub, or maybe even the crossover, but on rock and turning the volume up pretty loud the sub does make a sound that is a little hard to describe. The closest thing I can think of is "Maybe" it's the center of the dust cap flexing and making a little noise. Kind of like a snapple cap when you press it in, it makes a little pop noise. I noticed the sound free air as well, and could just very well be that the sub doesn't like higher freq. Not sure yet, but I will update if I can get the sound to either go away, or it just ends up getting masked at high volume. Overall, I'm happy with my purchase.