It's JL Audio. They're built like tanks, deep, very fast and tight. The newer versions use their room tuning DSP DARO (II) which is much improved over the earlier versions.REL is good- I had an SHO/510 but more subtle, driven by the speaker leads and did not have any tuning. SVS make a decent one with a decent phone based app to tune it with-but its not in the same league as the JL product imo and my experience. Depending on your budget you can also get the JL CR1 which is a pretty sophisticated - and tonally invisible- active crossover that will really tune the sub, the room and the main speakers.
