itd work if you had a preamp out or effects loop send and you take that and plug it into the pwr amp, I know the Spider 3 doesnt have that feature so you cant do that, honestly even if it did have that I wouldnt do it, it'd be pouring digital preamp and pwr amp models into a tube pwr amp, which isnt the greatest idea for sound. If you want the L6 modeling and effects with the tube design, get a Spider Valve, youll get better results. You got an idea going, and its not stupid, its just not the most practical, or best for what your probably wanting.