I have 2 computers hooked up to my dac (down from 3 - didn't use Moode very much on the Pi). I consider having the option to alter the digital filtering essential to maximizing the sound quality of one's system. It's cool too. Haven't dabbled quite yet in deconvolution but I'm sure that's on the way.
- Pi with an Allo Digione, running PiCorePlayer, coax spdif to dac. PiCorePlayer has the ability alter the type of filter (linear phase, minimum phase, everywhere between), filter slopes, upsampling etc. The ability to shift between linear phase and minimum phase results in a huge change in sound quality (on audiophile terms). Much more than a cable swap, linear power supply etc. If you can't alter this in your current setups then you are stuck with what the designer picked. All digital filters are wrong. I like being able to select the least-wrong one for my tastes. I like the sound of everything upsampled to the max the spdif can take, 176 or 192, even multiples, with a filter that's half way between linear and minimum phase. Not sure if the iFi Purifier will improve the Digione - would like to try.
- Minix Neo Z83-4, Win 10, fanless, cute. This runs Jriver, Tidal and is an HQPlayer NAA device, so nearly unlimited ability to choose the digital mangling I want. I prefer that to having someone else choose it for me and hope that their choice always matches the one I would have made for every piece of music for all time... Upsampling to 4X DSD is interesting. It always sounds better on acoustic music, but I often prefer plain old PCM for more electronic stuff. The output of this PC goes to an IfI nano IUSB3.0. In HQPlayer and JRiver I usually upsample everybody to the 356/384 family.
So then it goes onto a dac (Gustard A20H, longing for a Brooklyn DAC+) which further upsamples again, so I really have no freaking idea what the dac thinks when it sees data that has already been upsampled by a computer. The theory is that the less work the DAC has to do t he better, so have your high-power PC do as much of the heavy lifting as possible.
So, to upsample or not to upsample, that is the question. It's just so cheap and easy to get so much capability - I'd feel naked without it.