I was turned off from reamp'ing guitar tracks a while back when I found that I really couldn't hear the difference between guitars when they were reamp'd. After doing a bunch of research, I came to the conclusion that I must have had the output set too high on my DAW which was causing the transformer in the reamp to overload and was killing all the nuances.
This evening I was able to conduct a test by splitting my guitar signal (using a Radial ABY) between my amp/cab/mic and a direct injection into my interface. I matched the levels as close as I could so that they were both peaking at about -12dB. I then recorded both inputs.
I then ran from the interface out into my Radial passive reamp box and adjusted the level on the reamp until it had the same level going into the mic preamp.
The results are very promising. I still need to try it with 2 different guitars to see if you can hear the differences when they are reamp'd, but I think this is a step in the right direction.
It's a lot more work than you would be led to believe of just running the DAW's output into the reamp box and pressing record. You really need to watch the output level going into the reamp. (I think this has a lot less effect if you are recording with a lot of gain, as it will only add more gain and any tonal differences will be much harder to notice)
https://soundcloud.com/bena/reamp-test2