I have found CD players in the $200 range are good enough for my ears. I have several with different DAC's and a DAC on my pre-amp also. I have compard them carefully and the difference, if there is one that is audible, is not enough to be meaningful to me.
In comparison, I have a sub working at below 50 Hz and I can tell the difference when this is turned off, even on simply male vocals and at very low SPL levels. I find speakers improve dramatically up to around $1500. Above $1500 the improvements definitely diminish but are still audible. Unlike, CD players and SS amps, the differences between speakers of similar high quality from two manufacturers(at any price) are almost always immediately apparent and audible.
To me CD digital audio, after 25 years of evolution, is at such a good and consistent level of reproduction that it is now the recording/mastering studio quality, my room and the speakers that make the big differences for me.