The backwards passive DI works fine. It isn't as clean for obvious reasons but it certainly works. You can always try straight from your interface, slowly bringing up the output. If you want it to sound as good as possible as simply as possible then buy a reamp box. Otherwise try one of the other two techniques and see where the get you. You aren't going to hurt anything as long as you don't start out with everything turned up all of the way or send something that isn't a guitar out (drums could be bad). Worst case scenario you've wasted ten minutes.
Don't confuse yourself by over thinking this. There is nothing "unregulated" about your DAW output. It is effectively the output of a digital mixer with complete control of level.
Last edited by egan. : May 7th, 2012 at 09:33 AM.