I've noticed that there doesn't seem to be much information on this subwoofer around and I really don't know why as I have been fairly impressed with it having had it installed in my car for around 18 months.
First of all, if you are looking for a booming bass tube that will shake your neighbours windows and frighten small children, don't bother. This is a small, compact subwoofer which adds depth to music, but doesn't drown it out. If you are a bass junkie, the 250wrms power output will simply not be enough for you.
Nevertheless, it has performed very well for me. It was as very easy to install, as the amplifier is built in to the subwoofer. I also have the additional 4-channel amp, which simply plugs into the side and can power your front speakers too! This is a bargain at £40 and gives a complete amplified in-car set up all in one useful box!
The box itself is about the size of a standard 10" subwoofer, possibly slightly taller. It fits against the side of my Skoda Fabia boot nicely. Looks-wise, its not very pretty as it looks a bit like a heater, but it does the job very well.
It adds plenty of depth to all types of music from rock to RnB. For RnB, I find the bass control (which can be put just within reach of the driver to adjust bass levels as you please!) is always below halfway. However I do find myself having to turn it all the way up for rock music, and even then on certain songs I do find it lacking some oomph. But for 90% of songs, it is perfect. A CD is included which aids you in tweaking the gains and bass boost settings perfectly, and the "phantom centre" allows you to digitally adjust the sound output to make it sound better for the driver.
All in all, a great bit of kit for those who want to add lots of depth to their music, but who don't want a huge bass tube taking up boot space along with an external amp. The 4 channel add on amp, if you can get it, is a must.