I don't know if anyone will read this. This is very important information for this list of HDCDs.
The problem is that there are a lot of "fake" HDCDs out there. I have around 2000 albums on my hard drive. About 15 or 20 were HDCDs. But of those discs, over half were "fake" HDCDs. Please allow me to explain.
Pacific Microsonics (PM) invented the HDCD process in the early '90s. After that they started selling a special A/D converter that would include the HDCD codes. This converter was called the PM Model One and was limited to 44.1/16 output. Then in the early 2000s they introduced the Model Two that would go all the way up to 192/24. That was the only substantive difference.
These A/D converters were the best sounding converters available at the time and are still considered among the best today. They were designed by Keith Johnson, who designs most of the Spectral super high-end audio gear. In addition to just sounding incredible, they applied the HDCD encoding process, which can be broken down into the following items:
a) On-the-fly selection of the low-pass anti-aliasing filter. The machine would analyze the content of the music being converted and choose one of two filters to achieve the best sound. Contrary to the internet rumor machine, this does NOT require any decoding. There never has been and never will be multiple playback filters for the HDCD process.
b) Selectable dither levels and shapes. This was quite advanced for its day as most people were not aware of the importance of proper dither in capturing low-level signals. Again, there is NO decoding required or even possible for this step.
c) Perhaps the heart of HDCD was the use of two separate "compansion" (compression/expansion) methods. The idea is that the dynamic range of the music is compressed during the recording phase and then expanded back upon playback. One of these is Low-Level Extension (LLE). When the peak music level reaches -45 dBFS, the system boosts the gain by 0.5 dB. As the level drops the boost increases, to a maximum of 4.0 dB at -63 dBFS.
In theory this should be decoded for proper playback. In practice it almost never is used. Even quiet passages of classical music are louder than -45 dBFS. I have seen a handful of discs where the LLE becomes active for a few seconds as the song fades out. I have seen one classical disc where the LLE was active during the music. There were solo piano chords that faded away to nothing before the next chord was struck. Even with these I doubt that one would hear much difference between decoding them or not.
d) The other half of the equation is Peak Extend and it is active at very high signal levels. It really should be called "Peak Compression", because that is what it does. It takes the top 9 dB of the recording and compresses it down to fit into 3 dB on the CD. Then an HDCD decoder will expand it back to the full 9 dB of range. This is probably the only feature that might require decoding to achieve the best sound on an HDCD disc. I say "might" because unless the decoded music reaches a level of -9 dBFS, the decoder won't do anything. About half of the albums I examined that use Peak Extend (PE) don't ever reach levels that high. Examples include most of the early Joni Mitchell catalog. The other half of the albums that use PE have peaks that reach as high as -1 dBFS and will definitely benefit from decoding.
The reason that I know all of this is because there is a plug-in for Foobar (the Windows-based music player) that will identify which features were used on any album. Configuring the display is a little tricky. I posted some instructions at:
http://diyhifi.org/forums/viewtopic.php?f=2&t=2124
Now here is the kicker. When the mastering engineer is making an album, he can choose to use PE, LLE, both, or neither. Many, many albums are made using NEITHER. But the PM A/D converters still put the secret "subcode" into the bitstream that will light up the "HDCD" light even if there is NOTHING to decode!
That is why I said that about half of the "HDCD" albums I have (that light up the "HDCD" light) are "fakes". They will sound exactly the same on any CD player because there is nothing to decode. (Well, actually every CD player sounds different, but that is another topic for another day.)
So I hate to break the news to you. The fact is that this list of HDCD discs is just plain wrong. There are many titles that, while made with the PM A/D converter, were not made using any of the HDCD features and do not require decoding. For example on the first post in this thread, "Patsy Cline's Greatest Hits" was listed. This is not an HDCD disc and requires no decoding whatsoever.
Simply putting a disc in and seeing the light is not enough. The only way to know for sure is to use Foobar with the latest HDCD plug-in. PE is very simple to interpret -- it's either on or off. LLE is a bit trickier. Watch the gain setting in between tracks for a quick indication of whether it was used.
Sorry to break the bad news. It is just part of PM's slimy marketing practices. Rather unfortunate, as they had the best engineers in the world along with some of the sleaziest marketing guys in the world. But finally there is a way to know for sure how a disc was recorded and if it actually needs decoding. (This is why there are so many discs with no marking on the jacket that will light up the "HDCD" light. The mastering engineer used the PM A/D converter because he liked the sound, but didn't use any of the HDCD features because so few players have the decoders.)