You do not say what your source is! Assuming it's CD, might it be your CD player adding the HF edge? Regardless, a tube preamp will reduce the HF edge, but it will not remove the transistors from your SS amp. Transistors have their own sound as well. In short, yes, a tube preamp will warm your system. Be sure to try your choices in your own system to be sure you get the sound you seek.
Tube sound: Pre-amp vs. amp?
I'm just an audio neophyte, so bear with me on this question: If I want to achieve a "warmer", tube-like sound, do I have to upgrade BOTH the pre-amp and the amp to tubes? I currently have ss components (NAD) and would like to take the edge off the top, but keep the detail, especially in the mid-range.