Lots of good responses BUT it all depends on the matching of the CDP preamp and input on the amp. It also depends on the quality of the volume control in the CDP. The Shanling mentioned above had a poor volume control even in my highly modded one. It also depends on the preamp too. With some of the higher priced CDPs that have better volume controls, you will need a pretty good preamp to beat them running direct. I would not run an Audio Aero Cap MKII into many low end preamps an expect better sound than running it direct but maybe into higher preamps but this becomes a law of diminishing returns.
Won't preamps become obsolete?
I'm in the market for a new preamp because I want to upgrade from my Conrad Johnson PV10A. I listen mostly to vinyl but some CD and hopefully SACD some day so I need a preamp to integrate sources. As I look at the used preamp ads on A'gon, however, I notice more and more people saying that they are selling their preamp because they are going directly from a cd player with volume control into an amp. As vinyl wanes (never with me!) will the preamp follow suit or become more oriented towards integrating home theatre digital video and audio sources?