Whilst noting comments to my input of the NAD C399 that its not the warmest of amps (none of the Hypex are) it does also have an E-ARC HDMI, so probably simplest connection for you from the TV.
With regard to the speakers if they are similar priced in the US (they are in the UK) then might I suggest as an additional audition to the Monitor Audio 300 7G's the Acoustic Energy AE 320 and AE 509. When the NAD C399 was bought I had some slightly old generation Monitor Audio Gold's and we tried them against some borrowed for audition Acoustic Energy's and I was impressed enough by the difference buy my step-daughter/son-in-law the Acoustic Energy's when I could have just let them have the older Monitor Audio's.