Back to HDCD. Again,
Wikipedia has a good description.
My take, after trying to hear the difference between an HDCD decoded and not decoded, is that I can barely tell the difference.
On the other hand, it seems to me that when a mastering engineer opts for HDCD it probably means that he/she feels that the source material is of sufficiently high quality to warrant it. Perhaps also the engineer will take extra care and pride in trying to make the recording sound good? In other words, HDCD is an indication that the sound quality has a higher probability of being good.
