We like European! DD Audio and European distributor AI Group developed together a special model subwoofer to European market only. One of a kind subwoofer that has high sensitivity to give out more bass per every single watt used. Unlike other high sensitivity subs, 600e subs have also LOW FS to give REAL BASS and not only high frequency burps at the competitions. And of course with a price tag that is suitable for everyone. Newly designed T-yoke has solution that improves air flow and helps voice coil to stay cool. And as a very welcome bonus it also smoothens impedance curve and gives higher sensitivity. 700-series deep frame with big spiders makes it possible that these subwoofers have longer mechanical travel. Motor is a little bigger than regular 600 series has, and voice coils are Made In USA high temp-voice coils. With 600e you will definitely get more bass for your money than ever before!