Q: Tube CD player with DAC...

Will using a tube CD player as a transport and a DAC defeat the purpose of the tubes or will the tubes sound go across?
If the tubes aren't in the signal path, then I can't think of any way they can have an influence on the sound. Now, if the DAC in question has a tube output stage, that's different. Enjoy.
Only if DAC uses tubes.
The tubes in the cd player are only in the analog signal path not the digital. So the tubes play no role in the signal reproduction if an external DAC is used.