CD player straight into amps?

Absolutely! Wadia 27ix into McIntosh MC 2000.
I have an Audio Research SP 14 pre and a Burmester 808 pre. Both change the sound accordingly but don't improve it really. The best pre is no pre!

To Preamp or not , that is the question.

I am running my APL 3910 direct to my Pass Labs Amp via balanced interconnects.
There have been several versions of this APL unit, the one I have has a deep defined bottom end. Tvad, no way would I call it thin.

I have tried several Preamps , thinking perhaps they would provide extra gain and that would result in improvement.
But, they all degraded the sound quality.

My opinion is that each designed unit probably tackles the volumne control in different ways, so it really depends on the unit.

Ozzy, I did not say the my APL Denon 3910 running direct sounded thin. I said the preamp added body and musicality(to what was already there). The APL direct had some body, I preferred more body.

As I stated, I was in the clear minority opinion on this topic (although I was not a minority of one).

I'm in Tvads camp,there is definitely "something missing" without a pre in the chain.This opinion is solely based on experiences with my system and my musical tastes.

I have been an active preamp guy forever, but I have recently been experimenting with the Promitheus Audio Reference Dual-Box TVC for use in a second system. I have been playing with this little point-to-point hand-wired passive pre in my reference system while I am waiting to fully assemble this second system, and the quality and transparency of this inexpensive component have been a real eye-opener. (This thing plays WAY out of its price league.)

I think a high quality TVC like the reference version of the Promitheus component is a great alternative to a traditional active pre if you have high quality source components and the input sensitivity on your amplifier is compatible. A TVC can give you all the transparency of a direct connection between your CDP and amplifier. It is potentially a better alternative than a direct connection if the volume control on your CDP is not first rate or if the additional current and alternative input/output impedances offered by the TVC prove to be a better way to drive your cables, preserve dynamics and overcome some of the other drawbacks often associated with the elimination of a preamp or the use of a resistor-based passive.