Hi,
Making some experiments with guitar sound. I tryed to record guitar directly into Nuendo3 and use mic'ed guitar amp in insert of audio track. It alows to create the sound during mixing and there is allways way possibility to start again witch new sound. The thing I like best is parametric EQ before guitar amp that allows me something like guitar pick up modeling or distortion modeling. Have you tryed something like that? What about impedance matching between guitar amp and audio interface? Think that there shuldn't be a problem. But How could it affect the sound?
Lukas