Tboooe, regarding the newest ARC preamp line (LS17 and LS26) with the exception of the ARC REF 3, they are not "tube-like" at all. In fact, they sound very SS. Have you heard these in your system? The only one in their current line of preamps (LS17, LS26, REF 3) that sounds like "tubes" is the REF 3.
I state this as an enthusiaste of the LS26. I do not like the warm, syrupy, slow sound of tubes, so the LS26 is very much to my liking . But you state, "good tube preamps sound fundamentally different from good ss preamps. So while the Cp-700 is indeed a great preamp, it still does not give the sound that tubes do, which is what I am after." If you are after the sound of tubes, the ARC LS17 and LS26 are definitely not your remedy.
Be sure to demo in your system. And, if you think you are hearing tubes with the LS17 and LS26, I would state that it is the power of persuasion that is at work here. These sound more SS or at least equally as SS as the CP-700. Maybe you are just looking for a change of gear?
Best of luck. I really like the LS26 but my ultimate goal is to own the REF 3 unless ... (I'll leave it at that!)