First let me say I greatly appreciate your effort for publishing this plugin.
While trying this out, however I stumbled upon a snag:
It seems to me, that it doesn't provide a greater bit-depth than 16bit. And HDCD was invented in the first place to extend the 16bit depth of the original CD specification!
How can I say so, you ask?
Well, I use a sound interface which comes with a rather nice set of tools for measurements and analysis of audio signals.
http://www.rme-audio.de/img/techinfo/digicheck/bitstat.gifhttp://www.rme-audio.de/techinfo/digich.htm(This software can only be used with RME sound interfaces, so don't bother to download it if you don't have one of their products.)
Among these measurement tools is a display of the used bits for the actual played audio. This tool now displays that only 16 bits are used when I'm playing a FLAC file ripped from HDCD disc.
I am using the ASIO driver and I did maximise the volume slider, otherwise this measurement would not be possible since the volume adjustment changes the bit depth to 32 bit too if set to anything lower than 100%.
Of course I compared the readings of my instrument with other files, too see if my conclusions are correct.
I tested a FLAC ripped from a regular CD which gave the expected 16 bit reading.
Then I decoded my HDCD rip with eac3to.exe to a 24bit file and played that back. The reading for this was 32 bit.
Then I tested again the HDCD flac and it said 16 bit. Though in the status bar it said "HDCD active, Peak extension activated"!
In the preferences of MusicBee I checked "32bit playback" of course.
All of the files were checked with Winamp and ASIO output plugin too.
Conclusion: apparently the plugin fails to activate an output stream wider than 16 bit and such fails to fulfill its very purpose.
I don't have any idea if the plugin or MuscBee itself is to blame for this.
Addditionally, when the playlist advances from one HDCD file to the next, the "HDCD" display in the status bar vanishes. It reappears when playback is manually stopped and restarted though.