The HCCA is more powerful but not by much. They are both class a/b USA great quality amps. I have a reference 300 and I pushed my two reference ss12's with it and it was soo loud in my old exploder. I love the old reference stuff top quality stuff. the new stuff is junk.
Ya before I switched to Xtant I was a major Soundstream fanboy(still searchin for that Class A 100II sound). I'd say any of their amps up through the early Rubicon series is super stuff although I did have a Reference 404s take a dump on me. I bought the thing refurbished however, so it may have been posessed to begin with.
well i decided to get the reference 300 so my hcca is on ebay