Value of a preamp?

It can't add anything but can color the sound in a manner that some find positive.  

Jerry

It is still a short thread, but I would agree to some degree with the preceding statements. Insightful and helpful. In my case, achieving synergy between the ear, room and gear is with a good preamp/amp combo. No right or wrong. 

@OP - Well, impedance matching and volume control are two fairly critical functions. For the preamp naysayers, the reality is that any source component that can drive a power amp effectively has a preamp in it. So it depends on how good a preamp you want.

It's a specialist.  Volume control and source selection without degrading signal.

I added a preamp to my integrated amp and that opened my eyes to the impact of a preamp.

I'm an audio troglodyte. I like tone controls and most preamps have them, at least the ones I own!