difference between an active and a passive preamp?

Not at all, Mezmo. I'm not technical and it made perfect sense. Audioflyer: I was recently sort of in your position. Just a few weeks ago I was posting about my passive pre. As someone who went in blind, I can tell you what I encountered. Once I had it hooked up, the level of transparency people keep talking about was immediately apparent. My cd player was completely wrong, however, because of the impedance issues already mentioned in the thread. There is a loss of that in-your-face sense of detail and some roll-off. Still, I prefer it immensely to my previous solution. I ended up replacing my cd player almost immediately for better impedance. Alternatively, I probably could have gotten a buffer.

I'm not experienced with tubes or even the "tube sound." Some friends of mine more experienced with this have said that I've achieved a bit of a tube sound with the passive--I believe other passive pre users on this site have often reported the same thing. It's been interesting how loud it can get without being uncomfortable. Before, with my active pre, which wasn't a stellar piece of audio equipment anyway (Lexicon DC-1), the high end was just too sharp and fatiguing, especially at high volume. Now, more volume just yields more rich sound.

As has been said, an input sensitivity of 20 k0hms is a bit low. What's the output impedance of your cd player? What's your budget? Knowing nothing else, if you're interested in the passive solution, I'd do what Clio09 said.

Note: I misunderstood your last sentence, Mezmo. No wonder your layman's understanding suited me so well. ;)

To be on the safe side when using a passive preamp, I would want my source to have an output impedance less than 500 ohm, source output voltage at least 2V (this also depends on the input sensitivity of your amp), my amplifier input impedance greater than 50k ohm, and total interconnect length from source to amp not longer than 6 feet. In my system, I have a autoformer passive preamp, USB DAC with output impedance of 50 ohm and output voltage of 2.5 volts, amplifier input impedance of 100k ohm (with input sensitivity of 1.25 or 2.8V depending on the amp), and total interconnect length of about 5 feet. This way I can have all the transparency, naturalness, and openness of a passive without significantly losing dynamics of an active preamp.

Dracule1 said:

source output voltage at least 2V (this also depends on the input sensitivity of your amp)

Can you expand on this?

For example, if amp X has an input sensitivity of 1.25 V, 1.25 V from the source (eg,CD player) is need to achieve full rated power from your amp X. So if amp X is rated at 100 watts, it needs 1.25 V to produce 100 watts. If amp Y has input sensitivity of 2.8 V, then your standard CD player output of 2 V is not enough to get full power out of your amp. In this case you need active preamp, to provide that extra output to get full power out of your amp. Most passive transformer or autoformer preamp can provide an extra 6 dB of gain (stepped resistor, pot, or LDR based passives can't), so you can mitigate some of this. I'm not too certain on about how the length of the interconnects affects this. But I think longer interconnects will decrease the amount of effective volts the amp sees from the source. So I try to keep my interconnects as short as possible which also helps to prevent significantly losing high frequency response. If anyone more technical can find any error in my explaination, please correct me. I'm not that technical.