This is a thread best left for Dan Kennedy, but here are a few thoughts I have about preamps and equipment in general:
There are two extremes in basic schools of recording: accuracy vs. coloration.
Many people think that accuracy is most important for things like string quartets, symphonies, pipe organ and most classical music, while others argue that you can never duplicate the actual sound of live music when recording, so why even try? Go for the most pleasing illusion - even if that means altering the sound considerably.
Others (who work in electronic music) aren't even concerned about accuracy OR coloration - they're going for creating a particular mood. Any way they can get there is fair game. So is there a truth buried in all this somewhere? Yes, and no.
As recordists, our job is to capture the sound and try to create (or re-create) the excitement that the artist wants the listener to feel. We have a lot of tools at our disposal to do that task. We must decide whether accuracy, or something that compliments the sound, is the most desirable tool for a given project.
The medium determines the quality of the tools needed to do any job. If you record a metal group to a 4-track cassette recorder, you don't have to worry about the residual noise level as much as if you're recording a classical harp to a digital format. You also don't need a $5,000 mic to get a fair reproduction of a Strat plugged into a Marshall 1/2 stack.
To most people, the most important equipment specs seem to be a very low noise level, flatness of the frequency response, and low distortion, but in truth, most of those specs are meaningless during the actual recording process.
Why use a ruler flat mic to record something if you're going to add a ton of eq? Who cares about self noise, or the 1/2% distortion level if you're recording a Marshall stack that's putting out 10% distortion (and an amp noise level that can drive a gopher out of his hole at 40 feet)?
Yes, self noise, flatness, and low distortion may be important if you record quiet acoustic instruments, but how much noise, flatness, and distortion are tolerable is something only you can decide. If the particular sound is just a small part of a bigger picture, none of those criteria may even be important at all.
Try this: If you have one of the large diaphragm mics that are talked about on this forum, try putting on a pair of headphones, and getting right into the mic screen, say something like, "I am your father, Luke", or sing something softly, or just talk quietly.
Hear yourself? Well, surprise, that doesn't sound like you. Not at all. BUT, it's a great, complimentary sound. It might be really useful for something at some point.
OK, back to the original point of this thread.
You can't exclude coloration, or if something is complimentary, from any discussion of mics or preamps. In fact, at the lowest levels of making choices of mics and preamps, all you have to choose from is coloration, and complimentation. With just a few exceptions, low noise, flatness, and low distortion costs more money.
The preamps built into a Mackie are very good, low noise, flat, low distortion preamps, but their loading characteristics leave a lot to be desired. Some mics will sound totally different when plugged into a really high quality preamp. A Shure SM-57 plugged into
a Great River MP2-NV is an entirely different animal than the same mic plugged into a Mackie.
Great preamps (like the API, Great River, Neve, Millina Media, etc.) can turn an ordinary mic into a thing of beauty, or make an extraordinary mic beautiful beyond belief, while putting them both into a run of the mill preamp can remove all semblences of the "magic" the mic may possess.
So how do you know what's the right choice for your needs? It's a good question - I only wish I had a good answer for you. I don't. I can only suggest that you try preamps, using your own microphones, till you find the right combination for your needs, or start with a few basic colors of preamp, and learn how to modify the signal to make it sound the way you want it to sound.
For some recordings I've done, during mixdown, I'll run the vocals thru a SansAmp stompbox to actually introduce some distortion into the track. Why'd I do it? Because the vocal sound din't fit the rest of the music - it was too clean. Making the vocal track a little more gritty was the right choice, in that particular instance.
The Audio Buddy seems to be a fairly nice clean preamp if you don't push it too hard. Preamps like the ART, Joe Meeks, and a few others have a definite coloration to them. If you have a preamp, learn the settings that sound the cleanest, and the settings that impart the maximum coloration, and then learn how to dial in those settings to control and get the sound you want.
In the end, it's all about control and learning how to use the equipment you already own. Most people have more equipment than they really need, and that includes me. Leaps and bounds in recording don't come with the addition of new equipment; they come with really understanding what you already have and how to use it to it's fullest potential.
