I forgot add Im using a 2 channel Nad amp after the Dac.

That's great news, thanks for sharing!

Just for other forum members' clarity on what this all means to them (as MRX owners or possible MRX purchasers), how was the MAC connected to the MRX?

I forgot to add I go into a 2 channel amp after the dac.It is kind of a pain to change speaker cables to go from music to movies but I have 2 sets...one to the amp and one to the MRX. I just go behind the Triton and plug in what speaker cable I want to use.For me its worth the small inconvenience to get superb 2 channel audio

I had the Mac usb out to usb/spdif converter and the to digital in on MRX. My new set up I dont get to use Anthem ARC for music but it never sounded right anyway.I just do some EQ in my JRiver music player and the out to dac

I had the Mac usb out to usb/spdif converter and the to digital in on MRX

This may have been the issue. I am not an expert on these things but there is a lot of noise out there in the audiophile community about USB to SPDIF converters, and there are some VERY expensive ones on the audiophile market ($4000). From what I hear, something like an Audioquest Dragonfly USB DAC ($199) connected between your Mac and an analog input of the MRX, might have given you the stereo digital playback fidelity you were looking for from your PC-based music.

I always felt the usb converter sounded better. It does not colour the sound .It just make it more 3D ..its hard to put onto words. I understand it clocks better than Mac..which in turn produces less jitter. I just know it sound better to me. Mabye its in my mind(?)For mow I am happy the way it sounds. Plus, I like new toys Thanks for the feedback