From my personal experience. I had been using Arcam 192 CD player, not too shabby in its days, as a transport with Denafrips Ares II, it was big improvement over Arcam inside DAC. Then I bought Cambridge CXC transport and the improvement was really significant. Here I said it.
CD transports; do they really matter
In my pursuit of total sonic harmony, I have been investigating whether a CD transport ( to replace my bulky and aged Luxman CD player ) would be a good option. I had an interesting conversation with the manufacturers rep of a respected brand regarding his companies CD transport. He basically said its all in the DAC, the transport, as long as its not a cheap component, does not make much or any difference. So, I ask does it really matter?