I've had a Q12 myself, and it is a pretty good sounding sub but it's not out-of-this-world amazing. It doesn't have any special technology in it like XBL2 or LMS or copper shorting rings or anything to lower distortion. It IS designed reasonably well, otherwise, and will compare favorably to most subwoofers on the market (most of the other speakers have nothing like XBL2 either). It's a combination of a lot of things that most people don't think about. What material is the surround, how thick is the surround, how wide and tall is it? What is the cone made of? How thick is that? What size is the voice coil? How strong is the motor? What is the Q? etc. A lot of engineering goes into matching all the different components together properly, and also the precision of building the speaker. Honestly, I think it sounded pretty darn good with just about anything I put to it. It wasn't my favorite sounding sub in the world but never did I feel that it was bad. It has a bit more distortion than the more-expensive subs that I prefer (brands like Acoustic Elegance) which some people prefer (more distortion, I mean) in rap, but the distortion is not too excessive and it still works well for rock and such. I wouldn't recommend it for classical music and such, but it can do rap and rock pretty well in my opinion. Personally I pumped lots of electronic music through it such as the Crystal Method.