Largely due to the popularity of the Titanic kits, we have had many requests for Dayton Reference Series subwoofer kits. And why not-they are currently the most popular subwoofer line we carry. So I thought this would be a good time to introduce a Reference subwoofer kit, and at the same time explain some of the lesser-known but useful features of the Dayton HPSA500 and HPSA1000 subwoofer amplifiers.