I am guessing that at this point you do not own a dCS DAC.
There are no default filters. You are able to make up your own mind although dCS do supply suggested settings for a start in the User Manuals. However the available filters vary not only in regard to whether the selected data file is PCM or DSD but also in regard to the resolution. So PCM filter 5 for one resolution is not necessarily the same as filter 5 for another. For example filter 5 is an asymmetric filter for 44.1 but for resolutions of 176.4 and above that type of filter is filter 6 and filter 5 is then Gaussian.
In practice this may only be important during the set up period as once you have decided what filter you like for each resolution the dCS DAC remembers it and and it is automatically applied thereon ( unless you change your preference of course).