Well it depends on what you mean by "very similar", of course. I much prefer madVR and use it all the time, just to do proper bicubic chroma upscaling and a 3DLUT on low-end systems.
That said we have had users report that they cannot see any difference using various madVR options. To me NGU very high is a lot better than DXVA or whatever scaling the standard renders use. stax76 has been improving mpv as well, so that is probably better than Windows' EVR and similar.
Audio quality will not change with madVR. The important thing with audio is to convert and/or mix it as little as possible. Audio and Video quality are often player independant, with DirectShow players able to change both the audio and video renderers they use.
Sorry, I don't know your MPC-HC question. I am a rabid fan of Zoom Player myself.
