In the early days of computer audio Windows intruded on the signal path and changed the data. Software players like MC eventually learned how to stop Windows for changing the data, and the concept of "bit perfect" was born. That is pretty much a staple of the modern software player.
However, audiophiles have changed over time. They now realized that DACs use different techniques, including different filters, to produce their analog output. And, different filters can produce different results. Therefore, many DACs now provide a selection of filters that the user can select, depending on their own personal tastes. Many modern software players also now incorporate different filter options. This allows the user more flexibility than just what the DAC manufacturer provides.
JRiver has decided not to provide a selection of filter options. In that regard, many audiophiles will consider MC incomplete in its audio.
I fully realize that many people think it is wrong to provide output filters, either in the software or the DAC. However, others think it perfectly acceptable, given that the DAC manufacturers are already providing their own version(s) of the output filters. I do not want to get into yet another long discussion on this topic. I just want to point out that some people think MC is not "feature complete" in terms of audio.