in NOS tube DACs like Audio Note DAC5 there is no brick wall filter. Some SS DACs like TAD, Bidat and EMM Labs have perfect time domain response, as you know Ed Meitner used an adaptive digital filtering to have good frequency and time domain response. let me know if I am wrong...
I think in this industry we can find good sounding DACs and also good Transport like CEC TL0 but what we hear from digital is 90% related to quality of CD records and limits of CD format. the quality of most CD records are not good. one of the first Audiophiles who criticized CD Quality was Clark Johnsen.