I think you need a deeper understanding of recording practices. That is not at all typical practice for the classical albums I buy. I would not buy them if they did. Yes, for editing, short sippers of DSD are sometimes converted to DXD, then back again after the edits for final release on DSD.
To clarify this statement, for anyone that doesn't know: "DXD" is 24-bit 352.8 kHz PCM.
Once it has been converted to PCM for editing it should never be re-encoded to DSD, since DSD encoding is a lossy process.
If you are editing in PCM, you should be recording in PCM to begin with.
There is nothing superior about a high sample rate 1-bit format compared to modern multi-bit PCM.
An argument could maybe be made in favor of DSD when compared against CD-quality 16-bit 44.1kHz PCM audio, but not anything newer than that.
One thing to take note of is the current design of most DAC chips - they are actually based on processing delta sigma signals. (and mainly have been since the first Phillips 'bitstream' CD players back in the 90's) (It's certainly the way ESS 90XX DAC chips work)
So in fact a PCM signal actually requires additional processing compared to DSD (a delta sigma format) as the PCM signal has to go through a stage of interpolation into a delta-sigma format before conversion
Yes, but these are multi-bit converters, not 1-bit converters (technically they combine a
lot of 1-bit converters to create a multi-bit device) so there is no benefit to feeding them a 1-bit audio format.
As for upsampling there's really no point as you cannot create actual resolution by upsampling - if you have say 4 Hz and say upsample to 8 Hz really the only real data is the 4 data points the rest is really only guesswork. This was one of the problems with the first upsamplers where the algorithm was so basic that the upsampling actual cause 'smearing' of the original sound. Of course things have moved on but the basic fact that you cannot create real data remains
Upsampling
can improve things, such as DSP performed on the signal, however.
For example: you can use far more aggressive noise shaping when dithering if you are upsampling to a very high sample rate, than playback at 44.1 kHz.
Rather than having a lot of noise at ~21kHz, I can move it out to say 84kHz if I upsample to 176.4 kHz.