Passive preamps: What are the relevant numbers?


I'm trying to decide whether I am going to add a passive preamp to my system, but I've been reading that system compatability is very important. What numbers should I be looking at in the specs of my CD player (Rotel 1072), Amp (DNA 0.5) and Interconnects to judge whether a passive preamp might work well in my system?

I know that there was previously a thread about this, but it seems to have been deleted.
davetroy
The McCormack amps have a very high input sensitivity. Basically because they were designed to work with Steve's TLC preamp ... which is passive. As long as your CD player has an output level that is close to the industry stardard (or above it), at 2 volts, you should be fine.

Enjoy,
Bob
"As long as your CD player has an output level that is close to the industry stardard (or above it), at 2 volts, you should be fine."

Bob, that's the part that confuses me. According to the specs for the Rotel 1072, the output impedance is 100 ohms and the digital output is 0.5 volts, peak to peak. Are those the numbers I should be looking at?
Dave, if you are going analog out of CD player, then digital output is irrelevant. It is quite standard that analog output from standard CD players is at least 2.0 volts, you should be fine with a passive between the Rotel and DNA .5