I have spent years and money chasing down improvements in the CD player set up. From isolation platforms to tube buffers to running a digital line out from the CD player to an expensive and heavy separate DAC that was larger than the CD player.
I now have all my CDs transferred using lossless rips via iTunes to a commodity HDD, and from there I use a Sonos wireless solution to transfer the bit perfect music signals to my amplifier.
I still have a SACD player in my set up, but my C7s produce great music which sounds the same to me regardless of whether I play a CD in the player, or via Sonos. The sheer operating convenience of Sonos has resulted in all my CDs going into boxes, and the SACD player sitting idle.
I now believe that beyond a point pretty close to that obtained from even budget CD players of today, there is nothing to be gained by spending more on this part of the audio system.