I tried JR to convert DSD files to PCM and I was very disappointed by the results. Actually I tried most of the conversions JR has and I was not happy with the results. I am extremely pleased with other features JR has though, so I am happy to use JR for playback and other programs for file conversion.
Careful though when you say "Actually, many DSD files are recorded natively in DSD64,128, 256 or possibly higher." I have a problem with the term "native DSD" files. The term is used to describe music recorded directly in DSD format. But if you have a look at the music market in DSD format for most of it the source comes from SACDs, there are not many stores to offer DSD's. And SACDs most of them are not "native DSD" recorded, but either analog or PCM converted to DSD, so a conversion already took place before delivering the DSD files. There are some native DSD recordings, mainly symphonic music, recorded fairly recent, but older music re-issued in DSD format the source was analog or PCM, simply because DSD was not there when the recording was done.
It is true that most of my library is classical music. But, you seem to have some misunderstandings and some confusion.
SACD is merely the name for a particular Sony/Philips commercial format which exists on specially encrypted optical discs. Strip away the encryption during ripping of the SACDs and you have DSD64, which is the fundamental basis for the format. So, SACD is merely a proprietary container format for DSD64. The ripping process merely places the DSD64 into the user's choice of other, unencrypted container files on the hard drive, DSF being the most popular because it is taggable.
No, there is no such thing as stores selling DSDs. They sell SACDs, or download sites sell DSD files in containers, like the DSF or DFF formats. DSF and DFF files may be DSD64,128, 256 or higher.
It is in many ways analogous to CDs, which are just an optical medium. But, CDs may be ripped to FLAC, WAV, or other container formats for the 44k/16 bit PCM which underlies the CD. But, FLAC, WAV, etc. are also capable of higher resolutions than 44k or higher bit depth than 16, hence those containers are also used for the distribution and storage of hirez PCM.
There are a number of recording companies that record exclusively in DSD, such as Channel Classics, PentaTone, Telarc(now defunct) and numerous others. There are other companies like BIS, 2L, Linn and many others that record exclusively in PCM, with a final translation to DSD64 for distribution on SACD. Contrary to what you say, it looks more like about 50/50 to me. Some people care deeply about this distinction and avoid SACDs or DSD files not originally - natively - recorded in DSD. There is even a website listing many downloads recorded in pure, native DSD, many in Mch:
https://www.nativedsd.com/One other pertinent point. I do no "file conversions". I consider that a waste of time and disc space. I rip my SACD files to hard drive as DSF, tag them, and I normally play them with conversion in JR DSP Studio to 176k PCM. There is no new PCM version of the file created. I can change those playback parameters or play bitstreamed DSD directly from the files, but never do I create a new resampled or reformatted version of the original DSD file.