They're pretty well obsolete these days and getting to the age where electrolytic caps will fail though. A buddy of mine still has a couple of those plus some even older a/d/s power plates stashed away somewhere, wish he would get into audio again so we could use those for something.
I just have them on display in my entertainment center right now. Hard to see the 3150 on the bottom from the photo. I would like to get a Rockford Punch 60x2, a Soundstream Reference 500sx, and an MTX of similar size to round out the collection . I got the 3150 from an eBay auction by chance and I wanted a 302 to display. I got a 302 now and I need to either sell or use the 3150