That's sooo general.

How much difference?
You have to look at your rig as a whole. If your preamp is a 'hemi' engine that you want to put in a lawnmower, then you don't need a great preamp. However, If you are currently running a vacuum cleaner engine in an F-1 racer...then an upgrade may be in the cards for you. Your rig components will interact with eachother and is only as strong as its weakest unit. Always look at the big picture.

Which one?
What do you plan on using it on? A vocal preamp needs to be different than one used on drums and so on.

I wanna use it on vocals, like R&B singing, perhaps use it with my CAD M9 condenser tube microphone. Right now my mic is plugged into a Xenyx 802 mixer with its built in mic pre-amp?

The Xenyx is crap. Until you upgrade your noisy interface there is no point to a better preamp.

Jay-ri wrote: how much of a difference can a mic pre-am make? and what mic pre-amp is suggested?

The difference in pre amps are usually not as big as some people make them out to be, but when you start to add up 20-30 tracks the small difference become more apparent. To me its much more a matter of trying to stay away from really cheapo pre amps that will harm your sound, rather than what good pre amp will be perfect for the sound.

My favorite mic pre on the market is probably the A Designs Pacifica, but there are many pre amps that I would gladly use to make albums (API, Neve, LaChapell, Great River...)

Guitarfreak wrote: A vocal preamp needs to be different than one used on drums and so on.

I do not agree with this at all. Great pre amps will work on any source. Its is absolutely no problem to use only one kind of pre amp for an entire album. Some of the greatest albums of all time where made that way.

RonanChrisMurphy wrote: [quote=Guitarfreak] A vocal preamp needs to be different than one used on drums and so on.

I do not agree with this at all. Great pre amps will work on any source. Its is absolutely no problem to use only one kind of pre amp for an entire album. Some of the greatest albums of all time where made that way.
+1. The idea of using a whole collection of preamps is a relatively recent invention. For decades studios used the preamps in their (top quality) mixing desks. End of story.

As far as the original question goes. The amount of difference a preamp makes depends greatly on the sound source. If you have sources like Hammond organ or distorted guitar that put out relatively block-like waveforms the differences are very small. Even a cheap preamp can be dialed in to its linear range and will give a clear reproduction of the signal. The biggest differences in preamps show up in signals like human voice and drums that have sharp transients and large spikes. Here is where the amount of clean headroom makes a big difference. With a good preamp you can get a a clear reproduction of the entire waveform without either distorting the peaks or losing the valleys in the noise floor.

Now within headroom categories there are differences, (most common distinction is "colored" vs. "transparent") but those are relatively small. That is, if forced to choose, I'd always go for the preamp with more headroom rather than worry about the particular "flavor" I'd prefer. [Ed.: way to mix metaphors!]

I used to think preamps were not super duper important. I based that on borrowing my neighbor's API 512 lunchbox for a session. The individual tracks seemed fine on their own, but nothing that seemed amazing.

Then, I listened to the final mix and the difference was pretty big. All the instruments sat in their space, the drums really popped and the mix just sounded better than previously recorded mixes (using Demeter HM-1 and on-board MOTU pres).

I built my own Seventh Circle Audio API & Neve clones. Wow, what an amazing difference. I am now among the true believers in great preamps.

And I concur that using different preamps depending on the source makes a nice difference and ensures you don't get artifact build-up from a single preamp character repeated over and over again.

Pre-amps in my opinion is down to personal preference. Yes your sound is only going to be as good as your weakest link in the chain but if you really want to get a pre-amp, and lets face it we dont all have mega budget. For portable use and on multiple applications I would reccomend an ART V3. I think its a fantastic alrounder. But it is a cheaper variant and runs at low voltage so not as good as high end stuff. I use it for all sorts of things from snare, kick, guitars, bass, vocals etc etc....

Hope that helps.