Hmmm. heat issue seems odd for a class D amp. You may want to contact whomever you bought it from, or the Manufacturer with that one.. But speaking of DSP's, Give this a look.......
https://www.parts-express.com/dayton...audio--230-500
New on the market, and the price can't be touched! I just ordered one to put on the shelf in the garage. Hey, you never know when you're gonna need an extra DSP unit....lol