When turned all the way up it is truly evil, I was amazed on how loud a single 12" speaker can be and how much you can feel from a couple feet away.. This is why Ii called it the Evil Amp, I am sure when some Guitar guy gets to play on it and see what it can do, Someone will want one bad.
Here is a link to the Preamp,http://www.behringer.com/EN/Products/MIC200.aspx
There are several companies making basically the same thing in all kind of price ranges, I even saw this one for over $100 and as little as $29.99, I see some now on Ebay at $43.00 but others makers for $29..
While I am no Audiophile and I can't tell a set of RCA 6V6s from a set of Sylvanias like so many others can, I still think this sounds the same as using just a more powerful amp.
I might have to get me one or two. I could use two for my iPod and cellphone to warm their sound up some before plugging them into my stereo system.