For Chord DACs the following is from Rob Watts...
"For Hugo 2/Qutest the signal path is: 1FS to 8FS input > 16FS WTA1 filter (49,152 taps) > 256FS WTA 2 filter > 3rd order 2048 FS filter > pulse array noise shaper at 104 MHz > analogue
When an M scaler is connected, the WTA1 filter is not used, and it is passed through to the 256 FS WTA 2 filter."
What this means is that sending any file that is less than 16FS (705.6 kHz or 768 kHz) will cause these Chord DACs to upsample internally... Sending 16FS will cause the first filter, WTA1, to be bypassed... This also occurs with the TTs and Daves although the WTA1 fillers have more taps...
With some upsampling software you also get the chance to use various filters to "shape" the sound... Anything from Linear phase sharp to Minimum phase slow...
Choices are good as everyones kit, room, ears and brain are different...