Well, there are a thousand different opinions on upsampling and/or digital filtering. My opinion is that less is better. So, sending your files direct into the micro is the way I would do it. You then have the choice of filtering in DAC.. either 'bitperfect' which does no signal processing, no upsampling, no filtering, etc before sending the data on to the hybrid delta sigma converter, or standard and minimum phase, each of which will 'oversample' all audio as it performs 'anti-imaging' filtering before sending the data to the hybrid delta sigma converter.
So, when you upsample in software, you add extra steps to what already will happen in the DAC itself.
All that said, experiment and settle on what sounds best to you.
Thanks for that. No forced upsampling in software, bitperfect filter choice on micro is what is sounding best for now.
Now for the DSD filter settings - my personal choice is extended... I found the extreme filter to just subdue the music a bit too much.