Benefits of tube sound with SS amp with tube cdp?

In my opinion you will hear two similar but different tube like sounds. They will both sound good, the question is which sound will you prefer?
Different tube preamps will also sound different, and the same tube preamp rolling tubes can be made to sound somewhat different.
No one can really predict what you will like best and there is no right or wrong answer.
Good luck with your endeavor.

I used to have a tube cdp, tube preamp, and SS amp that sounded really good. I changed to a different tube cdp, passive pre, and the same amp and it sounds awesome.
First I changed from a SF Line 3 SE to Placette Passive and the transparency and overall musicality improved dramatically. No dozen tubes to replace in the Passive and the initial cost was far less. The sound was further improved when I replaced the SFCD-1 with a Granite Audio 657 tube cd player.
The output level from the SFCD-1 was good with the passive, but the variable output on the tube stage of the 657 is better. I never have tried the cdp direct to amp, because there would be no remote for volume.

My set up includes a Jolida JD100, an ARC LS-12, and an Odyssey audio Mono Amps(SS) and the sound was great.

A few months ago, out of curiosity (from reading threads here about the synergy of tube CDP, tube Pre and SS amp), I bought an Octal-based tube preamp (Mapletree Audio Design Octal 6A Triplex at http://hollowstate.netfirms.com/) for $435 and tried it in my system. I figure that if it does not work, I can take the loss and charge it to experience.

My system sounded so much better ever since. The body and warmth of the sound is like an exotic delicacy where it gets fuller and more enticing as the tube aged in time.
From the SS amp, the "punch" was ever present. From the tube preamp, the timbre becomes lush without loss of detail.

The cd player? You know how good it is already because you have one. But in my case, it is a "plus" per se.

Go for the tube preamp. You will not regret it!

....hope this helps....