How can you tell the quality of the parts?Open up both the sundown and, and the xenon, you will see that the xenon uses higher quality parts through my observation. With that being said, it is not a very efficient amp, but it is more flexible as it can run full power from 1-4 ohms. As for reliability issues, their is none. Several years ago the xenons had a bad batch. If you are content on using an efficient amp, get the sundown.
//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gifi see bigger wires in the sundown...therefore it's better