Newbie Question: Why do you need a PreAmp?

Is it possible to bypass the preamp completely if I am not interested in DSP? I know the new Marantz DV9500 with the latest Cirrus Logic DAC has a built in volume control, and other souces like my PC, and outboard Dolby Digital Decoder have their own volume controls, so I guess my question is why do I still need a Preamp? Does it somehow add a voltage to the input source, or is it some other thing I am missing here?


Vinyl Baby! :)

If not, if you like the sound skip the pre.
Preamp originally served several purposes, it was for having multiple sources, and for the Phono section, and to have tone controls and a tape loop.
Once the Phono section, and the tone controls were dropped the preamp was mostly a glorified source selector switch/volume control.
If you only have one source, and it has a volume control, the preamp is not needed.
(One issue is some sources do not 'drive' some amplifiers well... They wind up sounding 'thin'
If this is not the case for your combo, go for it.

If my 'volume sources' sound thin, and I decide to send them through my analog preamp, is there a possiblity that I could damage my preamp? I've heard that you should never plug a variable output into your analog preamp inputs: you’ll kill the preamp by overloading it’s sensitive preamp inputs. Is this true? I think I would also have the problem of double volume, right?


?? Your 'source' would have standard and variable outputs.
Use the standard ones from the source Cd player for the preamp. Every Cd player etc that I have ever seen that has variable outputs ALSO has standard line level outputs.
And the output from a line source like a CD player would not hurt your pre whether you used the varied volume controlled output, or the line level fixed output.
(I would guess you are talking about someone putting the output of one preamp or receiver into the input of another preamp... That certainly could overload the second ones input section!
I also run direct to my amp with a Resolution Audio Opus 21 CD player. I used to have a Krell KRC-3 preamp. This is a very good preamp, and it did add depth and perhaps a little 'authority' to the sound. However, it clouded the sound just a bit and I am one who likes to hear things crystal clear. I did like some of the things that the preamp did and thus am still casually looking for a preamp like, perhaps the Ayre k1 to insert into the chain

If the music sounds "thin"(not enough bass resolution) you'll want to add extra negative feedback and there you interface with active analogue preamp: The lower gain preamps have deeper negative feedback and "thicker" sound.
Preamp serves far more than a switching device and volume control. It is literally the heart of an audio system. Ask anyone who owns, for example, a Hovland HP-100 Preamp, CJ Art II, or ARC Ref 2 mark 2. Music takes on a continuity, flow, and emotional drive that a passive just can not communicate. I have done A/Bing with several top passive units and they seem clear but lifeless with little micro/macro-dynamics and other qualities that tell you "transparency" to an inferior source or software just does not cut it and "transparency" without emotion is pointless. Ask someone with a cheap or poorly designed preamp and they will scramble to a no preamp option which is somewhat of a loss since music, it has been correctly stated, is the "shortest distance to the soul" and your heightened emotion in your listening response tells you how close you are.
Source selections
Volume/balance/tonal control
Additional gain
Impedance matching
RIAA equalization for LP
Add pleasing distortion
In the 1960s, a famous designer of tube amps said "If it sounds good but measures bad then you are measuring the wrong thing" . Distortion is a point on a graph, a sample point like a frame from a movie, and does explain why most people prefer today's state of the art tube/tube hybrid preamps over DSP generated sound fields. Some have argued that it is how tubes distort that makes them so pleasing. I suggest that there is, not a small bit, of arrogance on part of some engineers going on here assuming you know what single point measurement contributes to better overall sound. That is why, many, if not most, serious designers of hi-end audio use listening tests to verify or refine an audio product including Sonus Faber, Audio Research, Conrad Johnson, Talon, Wilson Audio. Some things are truly explained by point measurements, the derivative in calculus speak, but can not explain the complex information under the graph, the integration, that makes for a totally immersed listening experience.