Direct Boxes and Reamp Boxes!

Thank you so much guys! Buying the Redeye right now

Winter-- I'm using a Profire2626. As far as I know, the impedance is quite fine on those, am I right?

From M-Audio

Inst. Inputs (Unbalanced) at Min Gain, No Pad

Frequency Response +/- 0.1dB, 20Hz to 22kHz
Dynamic Range 108dB, A-weighted
Signal-to-Noise Ratio -108dB, A-weighted
THD+N (min gain, no pad) 0.0014% (-97dB), 1kHz, -1dBFS
Crosstalk < -110dB @ 1kHz
Maximum Input level 13.7dBV, typical, no pad
Input Impedance 1M Ohm, unbalanced
Adjustable Gain >53dB without pad
Pad -20dB

Considering that, any changes in tone (weather good or bad) from using the instrument in vs a DI into the line in are from the coloration of the DI, since they are made from transformers. All transformers will color the sound which is why you only use a DI when you need it, mostly because you want the most transparent sound as possible. The problem is everyone talks about the lack of quality that an interface's instrument in would have. Unfortunately, using a DI into the line in won't make a difference because the line in won't be any better in quality than the instrument in and adding a DI if not needed would only make the coloration worse. Like I said before a DI is only needed when the input impedance of whatever you are plugging your guitar into is too low and loading down the pickups but as far as I can tell instrument in on most interfaces are 1M voltage followers which do the job of providing enough current and preventing the pickup from being loaded down, which is the only real purpose of a DI. The rule of thumb is to never add a transformer to a circuit that is not needed as they do all sorts of nasty things.