Passive preamps: What are the relevant numbers?

"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

I humbly suggest you search the archives.

In the context of your system, it seems the low output impedance of your CD player should be able to drive the amp. I'm not sure what your amps input impedance is, but if it higher than 40Kohms you shuld be fine. I would expect the Rotel's output voltage to be at least 2volts, more than enough to get full volume from your amps. You should try to keep the interconnect from the passive pre to the amps to less than one meter (the cable can be longer if you have low capacitance cables - less than 20pf/ft).

I'm not sure what your amps input impedance is, but if it higher than 40Kohms you shuld be fine

Do you consider this a general rule of thumb where passives are concerned, that they feed into loads of >40K ohms? Why is this?