I'm very close to buying a CXN, but am a bit worried about several reviews stating that the uprezzed sound quality is superb from every source except for files being streamed via Air Play, which numerous reviewers felt showed a loss of defintion and all around flatter, thinner sound. I suppose there's a chance this has since been fixed via a new firmware upgrade, but if that's not the case, has anyone found the 851N to be better in this dept?