Just installed a bluesound node 2i , quality not so good

I have I have bluesound wired to avr now, can I bypass avr and direct wire to amp? Can amp have two sources of input? Not sure it would be smart to do this?

I am being held hostage by my speakers holding out until they reach their full potential.  Captivity is challenging, expensive, and frustrating due to a lack of clarity in the marketplace relating to a vast maze of complex components.  This forum has proven to be of great value.

Would a used McIntosh d150 dac be a good choice to go with the bluesound 2i?

emergingsoul, what eq are you using with your Marantz? Direct? I’m not very familiar with Marantz AV receivers. On my Onkyo, I have various eq settings. IE; Orchestra,Acoustic,Theater,Direct. On the rare occasion I listen to stereo,I use 2ch Direct for best SQ. I hope I explained this right. 

@OP, 
As listed earlier, an Ayre Codex, now running under $1K used.
Or, a Schiit Gungnir Multibit used- for a little less used, should provide you with enhanced sound quality.
As far as the Mac DAC, I would keep searching. Though it would probably be an improvement, I think you could do better.
My 2 cents....
Bob