Soundigital 400.2S-4 EVO (D class) power amplifier (2-channel).

Soundigital 400.2S-4 EVO (D class, 4 Ohm) power amplifier (2-channel). 

Soundigital amplifiers have taken over the market of subwoofer amplifiers. 
Unbelievably small physical size, reasonable price and BIG POWER are th main factors in this conquest. 
Now the size of a powerfull amp is brought to a whole new level. 
More than 500 watts of raw power in a chassis that is so small it barely covers your hand. 
For an amplfier this small, finding space for installation is not an issue in any car. 
There certainly is room for power! 
If you want to completely hide your amp easily, this is your choice. 
More power to main speakers or an efficient amp for a subwoofer.