Some years ago I used a 2 channel Kenwood 12volt DC car amp bridged to put out 150watts rms to power a sealed 12inch sub. I used a 12volt DC crossover to feed the signal into the amp so that I was only amplifying the sub frequencies. All of this was powered by a RadioShack AC to DC converter that weighed about 20 lbs and cost about a hundred dollars. The crossover had a remote gain control that I adjust from my seat. All this was gear was placed behind furniture to be out of site. It was visually unappealing. It did not sound too bad, performance was more dependent on sub room placement than any thing else.