I don't think Peter ever released the Black REDDI. I've not seen it available. Peter is very particular and doesn't like to release stuff just to release it. But the differences are, as he puts it, the red REDDI is more like his take on the B-15 experience with a near flat response while the black one has a slight mid scoop that he calls his take on the SVT sound. The black one also has a lot more gain available and it can drive a power amp, whereas the red one is very specific about what power amps it works with and won't work with all of them. But that's OK...I didn't buy it to work with a power amp