Sorry I don't have PMs active . . .
One clarification: I don't consider 96kHz ideal, I consider 64kHz ideal. But very, very few converters support it, so high rates work fine, up to 96kHz. 96kHz wastes a bit of HD space and CPU cycles, but that's not critical anymore, so it works. Above that I would consider technically worse. I tend to work at 48kHz.
As for the Revox specs, let's just agree that it is not comparable to a mastering-grade 1/2" deck. It's a consumer solution that is comparable to consumer grade digital audio. -1.5dB at 20kHz is about the same as 44.1khz digital. Digital is flat down to 20Hz; most tape decks can't manage that. That doesn't matter at all for violin. Tape may have desirable euphonic characteristics; if so, these are distortions.
Dynamic range is a non-issue for any digital format in recording solo violin. I think my Soundblaster, used with care, would be fine in that respect--and it's a noisy piece of crap. Any reasonable tape solution would also be fine, provided that gain staging is managed properly (which is also a requirement of digital, but less critical at 24 bit).
OK, more interesting topics: polar response and its effects on microphone selection. I don't have much to say that was not said by the great Harvey Gerst in this thread:
https://homerecording.com/bbs/showthread.php?t=27030
But I know that is long. Instead, look at this page, while we are talking about the C414 series:
http://www.akg.com/site/products/powerslave,id,782,pid,782,nodeid,2,_language,EN,view,diagram.html
One of Harvey's basic posts describes the process of creating a directional microphone--it involves sound incident to the rear of the microphone arriving at the rear of the capsule slightly delayed so as to cancel with the arrival at the front. That is a frequency-dependent effect, and it creates a resonant peak. That large resonant peak is the simple case; it is further canceled by making a more complicated arrangement which reduces that large resonant peak into smaller resonant peaks. Once you are done, you generally have a fairly flat response.
Added to that will be resonances from the case, grille, and anything else the manufacturer throws in there.
The C414 (B-XLII in this case) has a series of varying resonant peaks, according to the polar pattern. Sometimes you select a polar pattern based upon the need for off-axis rejection. That varies in intensity and orientation--figure eight has near-perfect off-axis rejection at 90 degrees. It is useful in close-micing ensembles where isolation is desired, for example. Moving along to hyper/supercardioid, that has very good rejection at 120 degrees, very good for stage use where wedges need to be rejected. Then there is the usual cardioid, good rejection at 180 degrees, finally subcardioid and omni.
OK, so which do we use for a solo instrument? As you can see, the resonances vary according to the polar pattern. With a single mic in a good room (or truly dead room), you would select the pattern that complements the instrument the best. I have no way of knowing which that is in advance of a session (although I will allow myself to note the omni pattern's response lacks a presence peak

)
The complicating factor is stereo recording. Stereo recording involves first selecting a stereo micing technique, which will indicate a polar pattern. Further complicating is the off-axis mic orientation in many stereo recording patterns. That will yield a different response, in a lesser mic than the AKG, that could be a good thing.
Some mic techniques used for solo violin (and other instruments) are not true stereo arrangements, but rather spaced pairs, for example above and below the instrument, or near and farfield mics. In that case, it is not necessary to use identical microphones.
Microphones in the low-budget category that could be considered for solo violin:
- Small diaphragm condenser mics. More accurate transient response; more consistent off-axis response. Really cheap cardioid ones tend to have significant presence peaks, which I really think is a bad idea for violin. The cheapest reasonably flat cardioid mic I can think of is the Shure SM81, which is very commonly available used for about $200. Also popular, although I haven't used them, is the Oktava MC012 (darkish), and the MXL 603 or 604 (bright, but tameable). I believe the 604 is the model where you can get omni caps. That's true of the Oktava too; it used to be true of the Shure, but the omni cap for the SM81 is long discontinued and impossible to find on the used market. Audio-Technica has a range of inexpensive small-diaphragm mics that are worthy of consideration; we use I think 4041s as choir overheads (and off-axis pipe organ!) at church and they work well. They also have entries in their 20 and 30 series. I would avoid the AKG C1000, universally derided as perhaps their worst microphone. There are probably better choices in their range, but I don't know them.
I believe choices in polar pattern are good . . . but a reasonable cardioid mic used in a typical stereo configuration will be between 45 and 55 degrees off-axis, where they are flatter and darker.
- Large diaphragm condenser mics. Greater variance in off-axis response; slower transient response. Often viewed as euphonic, especially on vocals. Quieter than SDCs, due to higher capsule output. Not used as frequently in off-axis stereo patterns, but popular for techniques such as spaced pair (on drum overheads, for example), or on-axis stereo such as mid-side or Blumlein. However, slim pickin's for solo violin in the $100 range. How much is the CAD M179? People seem to like that one, and it's switchable pattern. Beware of the SDC hiding in an LDC body--not a bad thing per se, it could sound great. Just don't be fooled into thinking you will get the characteristics of an LDC. You might get something clever, or you might get an SDC with added case resonance.
Before we leave the topic of condenser microphones, you will hear recommendations for tube mics. Everybody loves tubes! I love tubes! I love tubes on violin! Some designs are better than others, but I think $100 is probably pushing it.
lastly:
- Ribbon mics. Smooth high-frequency response, but often not much of it. Low sensitivity. Most are figure-eight pattern. Ribbon mics are hugely trendy. I'm not a ribbon fanboi, and that's not because I make condensers. I've actually done a lot of work with ribbon mics, but at $70 (watch for sales) the Chinese have cornered the cheap end of the market. I think they are good at what they do, I just don't think they do everything. People that use them on drum overheads, I think they should buy better cymbals

but that is my bias.
On violin, they can be useful on a bright instrument where close-micing is required. They're good at instant fiddle. I would not select one of the cheaper ones for distant micing a violin, there's just not enough there. Beyerdynamic makes a couple of midrange models worthy of consideration; I satisfy myself with an old Shure 315. Perhaps once you've got a setup and are looking for another tone, but before then I'd look in the SDC range for a primary pair.
OK? Interfaces I already said I don't really know. I think in the same price range they are probably comparable. On the lower end, you probably won't get a brilliant analog front-end, but for your use I don't think you need that. USB vs. Firewire is not gonna be an issue for stereo recording.
Ordinarily I would never recommend mixing on headphones, but if you're not doing much processing on a stereo recording, you're probably fine. Just don't do any crazy EQ changes without rechecking in your car or something. Actually, cans might be good, since reverb stands out more, you will resist the temptation to drown your recordings with the cathedral setting
Building can amps sounds fun

. . . I really am not quite sure how I stumbled into microphones. I'd rather do a small metal box with tubes sticking out of it in strange places . . . but it's a living, I guess.