If possible I recommend you audition any CDP that you will use direct to amp before you buy it (or atleast buy it used so you have the option of selling it without too much of a loss). I have yet to run a CDP/DAC direct to an amp and prefer it, long term, over using a CDP/DAC with a preamp in the chain.
A few I have tried: Wadia 850, Benchmark DAC1, Apogee Mini-DAC: Just my two cents.
A few I have tried: Wadia 850, Benchmark DAC1, Apogee Mini-DAC: Just my two cents.