It all depends on the CD player involved AND (naturally) what tubes are being used. I have found a HUGE difference in tubes in my stock JOLIDA tube CD player. The best sound came from rare 12AX7 versions and it was immensely different than even the next vintage tube version tested.
Sadly unlike preamp applications, most modern day tubes did not sound good in the CD-100 (to me). I REALLY like the JJ ECC803S tubes in many preamp and amp applications but they sounded just blah in the Jolida. The closest to modern tubes was the recommended Phillips JAN versions. These at least got the player to be interesting.
Further sonic improvement after that required vintage tubes to extract more juice out of the CD listening experience. Of course at some point the tubes start costing a significant amount compared to the cost of the player so that needs to be factored in as well.
I guess it all depends on what type of sound you want to achieve from any CD player. I find non-tube CD players to be clinical at best and I like my CDs to sound as close to my LP sound as possible. Why? Because a lot of modern day music is simply not available on LP - even imported.
Also, for test purposes try some of the Mapleshade CDs. Although rather "dry" sounding when the CD playback experience is "right" they really do convey the "in studio" performance very, very well. After calibrating to something like the "Mojo" CD I can usually then pick out all the processing and the like done in other CDs. Not all of it is bad mind you, just different from a "purist" perspective.
