Sound without the Preamp ?

No preamp can improve things unless there is something deficient about the output drive capability of your CD player, and only if driving the preamp is easier than driving the power amp. It seems that your Accuphase CD Player drives your amps fine, so why degrade things with imperfect cables, connections, and preamp?

What you are saying Carl, sounds right to me, but depends on how the DAC achieves the volume control. For example in the early Theta DS Pres, they used some OP47s in the first analogue stage after the DAC. The OP47s drove both the fixed line out and a preamp stage. The preamp stage had switches, balance pots, a volume pot and then a further line stage using BUF03s. To my ears the sound was seriously degraded between the fixed out and the pre out. In certain cases, using the fixed out into another preamp or even into a passive was superior. The gains from having the pre section in the DAC were minimal to non-existant depending on whether you used a superior preamp to Theta's preamp stage. How do Resolution do it?

I have had similar experiences with lack of drive from passives, but passives can work very well with tube power amps due to the high input impedence of the typical tube amp.