XXHighend software upsamples to 768Khz and it normally works with a filterless dac (Phasure NOS1). iDSD has 3 selectable filters, maybe a 4th option (no filter) could be implemented to be paired with this special type of software (or others like HQplayer, etc...).
The iDSD micro includes a mode we call "Bit-Perfect."
In this mode no digital filtering is applied.
This "no filter" option is active and the only option for sample rates from 352.8KHz upwards.
For lower sample rates you can select this option or one of two different digital filters.
Just try them all out and see which you like.
Edited by iFi audio - 6/30/14 at 9:14am