Can't speak for PS Audio, but my recent experience with Monoprice (quite nice, and very cheap), Wireworld Starlight 6 (similar to Ultraviolet 7, I think), and Apollo AV Lightning is that they do look different and sound different. The Apollo and the Wireworld are both better than the Monoprice. Visually the colors are more saturated and the edges of images smoother, less grainy. Not hugely better, perhaps, but noticeable to my wife and I. Note that I have a very high-rez audio system, and a top line late model panny plasma. I'm not sure these differences would be very apparent on a lower rez system.
Sonically: smoother, clearer, better focus.
Worth spending the $ for the level of improvement? Maybe not for many systems, but the Apollo AV are fairly cheap, and very cheap on closeout, and do give my system a bump in quality.