OP, sorry for making a mess on your thread. I don't keep up with the USB vs. Firewire interfaces, they change models a lot, I don't use them, so . . . find one you like and go with it. Get the best room you can to record in. The rest will fall into place.
You don't need to worry about the rest of this post, but I can't let some of this slide:
Even if you closely manage the acoustics, I'd still be leery of using an omnidirectional mic. They do have flatter response, usually, but there are trade offs, like they are going to be much more sensitive to room acoustics, and placement vis-a-vis the instrument (what happens if you move around a lot when you are playing?).
True with respect to room acoustics, but false with respect to instrument position. Indeed, a cardioid microphone by definition has a greater difference in on- and off-axis response. An omnidirectional mic varies much less (though still some). Therefore, if you move around a lot, the cardioid mic will result in a greater difference than the omni. It's even worse if you wander into the nearfield of the cardioid mic, where there is proximity effect.
Large diaphragm microphones have a greater difference in on- and off-axis response as well. This is not to suggest a LD mic cannot be used; of course they can, and often sound good. But one should be careful not to confuse the euphonic character of a particular microphone with the physical qualities of that type of mic.
Regarding acoustics, I agree that to properly capture a good classical violin sound, some distance is required. The greater the distance, the more the room will come into play, irrespective of polar pattern of the mic. If your room sounds boxy, the cardioid mic will reject boxy sound from the rear, but still pick it up from the front. So what have you gained? Not very much, really. The primary requirement is still a good room, not a particular polar response.
Perhaps I should point out that Shure and AKG both recommend primarily cardioids for acoustic instruments. Naiant recommends an omni, but that is all they make.
Hmmm, is that because Shure pioneered the Unidyne capsule? Or that, as a company, they have primarily a live sound orientation? I don't want to dump on Shure, they make great mics.
My Shure KSM141 is switchable pattern; I believe they recommend it very highly for acoustic instruments. I haven't switched it to cardioid in a very long time. The AKG 414 mics are switchable pattern too . . . maybe there is something to these other patterns after all . . .
I looked at the M-Audio box you refered to in your first post, and even if one accepts mshilarious' argument that sample rate does not matter, and his suggestion of 88.2KHz or 96KHz (if it does not matter, why not just 44.1KHz?), then the MobliePre still won't cut it.
You don't need to accept my argument, it is demonstrable. I have done so in an old thread here somewhere; Dan Lavry has argued the point quite convincingly. 44.1kHz does work fine. It has better frequency response and dynamic range than your suggestion below.
For violin practice and listening to yourself, if you have the funds, I'd go so far as to suggest getting a friend who knows what they are doing, and finding a good, really good tape deck. Like a Revox A77 or B77 (made by Studer), in very good condition, the mics you need, a phantom power supply (fairly cheap) and recording direct to tape. Get the recorder serviced, aligned and tweaked for whatever tape you are going to use, I recommend something like RMGI SM911.
I don't even need to discuss sound quality (I presume it would be OK), but this is a rather preposterous suggestion for someone who want to spend $100 and use a USB interface. And they would still need to burn a CD, unless they can send the tape reel for their audition. And if we aren't talking the high-speed versions, the noise and frequency response specs suffer. Leave that stuff for serious analog hobbyists handy with a soldering iron, not working musicians who want a simple solution.
