We had a Cary CDP come to a g2g years ago, it had switchable DSP, upsampling up to 768kHz. "None" was the best sounding setting. Shutting off the DSP always sounds better to me.
The ESS SAbreDAC has a different way of reducing quantizing noise, and it works well. You get the natural tizz-free treble, but no loss of life and edge. This explains it if you're curious. I can't understand it.
http://www.esstech.com/PDF/sabrewp.pdfPure DSD is technically excellent, but few pure DSD commercial recordings available, not the type of music I listen to. Ripping SACDs with playstation isn't worth the effort to me, because most SACDs are reissued PCM or analog recordings anyway.
I have to choose a playback method focused on where the music is: redbook PCM. There are excellent PCM techniques like Sabre, Ayre, which make redbook sound plenty good enough for my needs.