Hi
If I have my info right the hdcd algorythm massages the sound to create what essentially is an upgrade from 16bit which is what the cd plays at normally and a quasi 20bit which is the hdcd thingy.
In another room I have a toshiba sd5109 dvd/hdcd player which i use also from time to time mostly to play hdcds. I had that player connected to a reciever in that room from the coax connection and was always wondering why my hdcd's didn't sound as detailed as when played through the pc. I went to the hdcd.com site and found that i had connected it incorrectly for the proper playback of hdcds because i was using the digital connection.
Once i added the analog out from the dvd player connection (i didn't have to disconnect the digital, I just used a separate input on the reciever), these hdcds came to life as they had on the pc. All of this to say that YES, I deffinitely notice a difference but I have always used a dvd player to play cd's.
One more thing. If you record your hdcds to the hard drive using Windows lossless in the wma options section, you will notice that the kbps is much higher than a normal cd.
Peter m.