CD direct to monobloks?

Try the different possibilities and let your ears decide. You can't hurt anything. Do make sure the volume is turned down on the Shanling or Primare before firing everything up.

Your old Adcom was a decent preamp. Things may be better with or without it. Good luck.

It all depends on how good the variable output stage of the CDP is and how it will match with the input impedance of the power amps. This is very important and could make or break a direct-to-power-amp setup.
Going power amp direct will be the shortest path and will require less interconnects, which is worth considering both sonically and financially, but it's not all that matters.
Technically all combinations you mentioned are viable, it will be for you to try them and decide what sounds best *to your ears*.

Hi Tiofelon, ordinarily this can be a great idea, but certain requirements must be met or else it's plainly not worth it. What you stand to gain by this method is the elimination of an entire component from the signal path (preamp), which, unless you've already spent a ton of money on a truly first-rate one, you can expect to get a good gain in overall transparency at the very least. However, if your CDP uses standard 16-bit processing, then any reduction of volume in the digital domain will reduce the volume by reducing digital audio resolution, quickly darkening the sound quality. For example: reducing the volume by 2db reduces the resolution of a 16-bit chip to that of a 14-bit chip. But, if your CDP uses, say, a 32-bit chip, then you can reduce volume as much as 16db without altering the sound quality at all (if you don't use oversampling). More viable still are the new 64-bit DAC's and players now on the horizon.

To see if you're a likely candidate for bypassing your preamp you can try an experiment: take any CD you know is comparatively quietly recorded and hook up your CD straight into the mono's, but be sure to start with your volume on the CDP all the way down. Try a track that starts off low in volume and slowly builds, if you can. Gradually increase volume until you get to either the loudest point you'd ever be willing to listen to it or as loud as your system will safely tolerate. If you can consider this volume level to be satisfactory to you in the long run as a maximum for your tastes, then you can very likely benefit from going preampless with your system the way it is. But, if that max volume level is in fact too low for you, even with normally recorded CD's, then you'd have to consider some future gear swapping to get it to come out right (either a different amp with a higher gain, or speakers that are more efficient, or even both, if you needed or wanted to).

Main issue is the volume adjusted in the digital domain? or the analog?
If digital, the problems of major loss of resolution with digital attenuation is as mentioned by others.

Otherwise, if it is with a standard analog form, no problem, except the cheap analog volume control likely present in the Cd player.