Best preamp is no preamp: always true?

If CD playback is your only source then you'll just need to get an expensive CD player with high output + volume control. In this case, the "less" component is better off.
This is different from having a passive preamp. I would go with that than having a passive preamp in between the sounce and amp.
The ONLY drawback is CD player choice. You will be limited to less than a dozen of expensive players to choose from.

As far as DAC goes, it is same idea as CD player with volume control. In this case, you'll be limited with DAC that has high output plus build-in volume control.

We have the same fancy (or as they say in the car industry, "pants") CD player as TVAD, and also find that we prefer having the preamp in the chain. It allows for better separation of the instruments, a preferable 'gain floor' as a complimentary support to the amps, and it conveys a more meaningful heft and density to the music. If we run direct--and our player does have an outstanding hybrid attenuator--the soundstage collapses, and on anything other than light chamber music, vocals or soft jazz, I'm just not feeling it. We take the preamp out, and it sounds like the music is struggling to get out, losing a sense of ease and realism in the process.

Some people will choose a configuration according to sonic preferences, while others wouldn't think of adding the preamp in the interest of maintaining a purist's approach. As TVAD suggests, you'll have to decide for yourself.

I have never heard a situation, where price was not a limitation, where NO preamp or where a passive preamp was superior to a really good, system-matched linestage. I know the mantra about sufficient output and compatible input and output impedance and short cable run, etc., but even in systems that don't need any gain from source (like mine), a good active linestage simply sounds more dynamic, projects a more realistic image, and pulls the listener into the performance in a way I've not heard passive linestages do. I suspect that the putative superiority of passive units may be a superiority AT A PARTICULAR PRICE POINT, but not absolute superiority.

Now, as far as NO preamp at all, with digital sources, one would have to consider whether the volume control is digital or conventional (variable resistance). I don't know if it really is the case, but a lot of listeners claim that the truncating of low level bits to achieve digital volume reduction is not sonically desirable, so playing the source at maximum volume and attenuating with an outside volume control is superior. If the digital source has an analogue volume control, I suppose the issue is whether that volume pot is better built than that in the linestage it is hooked up to -- if it is inferior, one again might get better results by setting it at maximum and using the linestage volume control to attenuate the signal.

Check out the discussion and review of a passive inductive preamp in the January 2006 issue of Stereophile.