The select is a different animal with the CSP in front of it, in my system. Timbral naturalness, dynamics and "slam" are greatly improved. The upper register of a cd source is also far more tolerable, besides being much more natural.
Additionally, I find that with a preamp with gain, the volume pot on the select can be backed off to around 80% or so, where the select hits its most musical sweet spot, to my ear.
Every now and then I bypass the CSP as a reminder, and it's always the same answer.

If you were to hook up an SE84CS directly to a source, I'd recommend vinyl (course then you'd need a phono pre).
Karl