Best preamp is no preamp: always true?

I have found that in real life passive pre's can sound very thin and bad. I'm sure it's system dependent, but if the impedances don't match well, it will sound bad.

Sogood51, your statement doesn't say very much.
"Passive volume controls are better than all but the best active preamps. Passive volume controls do not work well in all systems"
It is like saying French bordeaux is the best red wine out there but it is not for everyone.
How is that better than all and yet it is not competetant in some system?
Would it make sense to say that best active is better than all passive because it is suitable for all systems?

in my opinion, regardless whether the linestage and volume control are in the CD player or preamp, the quality of these parts are key. if a dedicated preamp has a better linestage and volume control than those in the CD player, the system will most likely sound better with it.

Not at all always true. It really depends on the driver stage of the source, which is often a cheap OP amp. Furthermore, volume controls on CDP are often in the digital spectrum, which means that when you lower the volume from full, you are affecting (lowering) the sampling rate of the digital signal.
There are sources out there that have real analog volume control and exellent driver stages... where a good pre-amp might just get in the way of the music, but I think it is more the exception than the rule.

Actually SoGood also answers the question in favor of preamps.

You have to spend what he calls "big bucks" to improve over a well designed passive volume control.

Note first the volume control has to be well made/designded. Note also that if you have the bucks to spend a preamp is better even in his opinion.

I personally also want/need a preamp. I just don't listen only to CD's. Also a lot of CD's are poorly engineered. The good preamp will make those CDs sound better than the raw data.