difference between an active and a passive preamp?

A very good question, After having owned some of the finest tube line stages,
and almost every type of passive, and given that I have low impedances
sources with strong analog output, short, low capacitance IC from "pre
to amp, and a sensitive (1v) amp with 100 kohm input impedance, I'm not
sure what an active, any active can do to make the sound truer to the source -
warts and all. What an active will certainly do as add a coloration (many
different flavors) that, while undoubtedly a distortion of the source signal can
be, for many people, very pleasant to listen to, and it does not matter if they
believe it is a move from "true to the source" - they like the way
their actives sound and that's all that really matters. Me, I prefer to take the
preamp (as best I can) out of the tone equation and deal with the Source,
amp, and ICs for the sound I want. The best passive I've tried? The Lightspeed
Attenuator. But I have not stopped looking......

Wow, guys,this has been really helpful and insightful. I'm learning! Actually, I should have read this before I made my purchase!!! I got the canary passive 200, and what a disaster! the sound was awful. A huge mistake! I chalk it up to a learning experience. Now, I am thinking of either a nad 165bee preamp to go with the nad 270 amp or maybe a tube pre that would be COMPATIBLE SYNERGYSTICALLY! I don't want to make another mistake. Because I don't really have an engineering background, and for that matter, don't understand the "electrical concepts" to ensure comptability, I'm going to first clear it with you guys, if that's ok. I love this hobby!
Can you guys recommend a good tube amp that would compliment nicely my nad c270 amp? Or, should I just sell the amp and go with a nice tube integrated? I prefer the former option for now. My budget is 500 to 1,000 max.
Thanks very much.

You tried the Canary with the NAD270? What is the sensitivity of the Quad
22s?
They don't need much power, do they? As for passive, I think you would need
something like the Goldpoint with a 10kohm pot and short ICs to drive the
NAD properly. I may be wrong about this, but I think tube amps are generally
better suited to passives, but if the Canary had a 50kohm pot, it would not
work too well with an NAD amp. I wonder if a used Cayin integrated will be
enough power (40 watts of so tubes) to drive the Quads. IMHO, if you want
tube sound you are not going to do with an SS amp, certainly not at your price,
and really even at higher price points.

Another active tube buffer that is getting some attention is from Dodd Audio.

I have found that my system when using some passives is more succeptible to noise (ie. RFI, grounding issues, etc).