My experience has been the same as TOK2000. I have never had any luck running a cdp direct. Pre-amp does more than just control volume it is really the first level of control in your system. In my system the pre-amp has always had the biggest impact on performance. I could use a mid-fi level amp, high quality pre-amp and get astonishingly good results but if I used a mid-fi level pre-amp, high quality amp I got poor results. Even the audio aero, wadia 861 sounded compressed and lost substantial depth in soundstage running direct. Just my two cents.
Chuck
Chuck