The great news is that it's nothing that money can't fix. Many CD players (and CDs) have a glare or brittleness that can be annoying. I had good success with a modified Sonos fed into an NADM51 as a digital source but the Sonos lacked the ability to play higher resolution files. Therefore, I recently sold the Sonos and went a different direction.
My digital "chain" is now an external hard drive (and some thumb drives as well) fed into a Bryston BDP-1 which is connected to the NADM51 with a balanced digital interconnect. The NAD outputs via balanced cables to a Bryston MP26 pre-amp. My amp is a Brytson 4SST2 and my speakers are Harbeth SHL5s. My interconnects and speaker cables are all Signal cable.
I also feed the NAD with an Oppo 83 using a Wireworld HDMI cable. This allows me to play CDs, SACDs, and DVDA through the NAD and this also sounds great.
I may not have answered your specific question, but I think you start with the source and work your way thru the chain. I'm happy with my result.
My digital "chain" is now an external hard drive (and some thumb drives as well) fed into a Bryston BDP-1 which is connected to the NADM51 with a balanced digital interconnect. The NAD outputs via balanced cables to a Bryston MP26 pre-amp. My amp is a Brytson 4SST2 and my speakers are Harbeth SHL5s. My interconnects and speaker cables are all Signal cable.
I also feed the NAD with an Oppo 83 using a Wireworld HDMI cable. This allows me to play CDs, SACDs, and DVDA through the NAD and this also sounds great.
I may not have answered your specific question, but I think you start with the source and work your way thru the chain. I'm happy with my result.