what's 'Active preamp' vs 'Passive preamp'?

The general definition of 'active' and passive' is similar to the audiophile definition.

Passive components are resistors, capacitors inductors and transformers, none of which requires a power supply in order to function. Passive preamps are made of these devices.

Active devices include transistors, integrated circuits and vacuum tubes (among other things) require a source of AC or DC power in order to function and their inclusion in active preamps is what is indicated by the AC cord.

Actually, you can make the volume attenuation even simpler - avoiding a "box" and having to add another set of interconnects. I have a pair of "shotgun" attenuators which sit between my interconnects and my amp.

Attenuator in my System

Thanks for the responses.

The main reason I asked this question is because I was wondering about not using preamp at all. That question led to this question.

I actully posted another question on that subject, but no response yet.

I'll kind of repeat what I said on that posting.

I'm looking at some of the newest high performance DACS such as Benchmark DAC1, Bel Canto DAC3, Slim Devices Transporter, etc, and I noticed most of those DACs have built in volume control with remote.

So, I was thinking that I can connect these DACs directly to my Power Amp eliminating preamp entirely.

I was wondering what's the implication on that approach?
What'll be the pros and cons?

Is it better because I'm skipping additional device that I don't need? or A good preamp somehow does some good thing to improve the sound quality?

There is just something to be said for a good active preamp IMO. I have tried passive ones and they did not float my boat. I have used CDP directly into amp and it was missing something. Over a period of time it sounded lifeless or sterile as did the passive.