If you ripped your HDCD discs with dBpoweramp CD Ripper, be sure that the HDCD code option is checked. Open the program -> Menu button -> CD Ripper Options -> Meta Data & ID Tag [options] -> Write ID Tags and check the HDCD option.
I have actually done that with Foobar 2000, with HDCD plugin. Sent new 44.1 24 files to a roon monitored folder. Listened to original, and file. Original CD sounded superior. I am told there is more to it than adding 4 bits. Perhaps dbPoweramp solves this.
I may not have explained this well. DB Poweramp will read your existing files, decode them for HDCD, and create new files with a greater bit depth. It is these new files that you will send to your opponent
ffmpg and dbpoweramp use some kind of “reverse-engineered” decoding of HDCD. So they effectively remove the original code from the file. Theoretical benefit: the files will be 20 Bit / 44.1 kHz. Downside: Players that natively decode HDCD will not detect the “decoded” files.
That’s the idea. There should be no need for an HDCD compatible DAC to decode the HDCD info, since all the information resides in the larger, decoded file that is compatible with any DAC.
At the last California Audio Show, I spoke with the folks from Reference Recordings, who are the experts on HDCD. Unfortunately, they claim that the software used by dBPoweramp is inherently faulty. So, in the absence of hardware HDCD decoding, it’s best to forget it and play the CD rip without decoding.