I've done this exact same thing - almost. I was running it the other way out of my mixer and wondering why I was getting 2 lefts. Took about a half hour of button pushing to figure it out. Luckily most of the 15 pages was figuring out a cheap workable setup.
DMB - about your current setup,, I'm wondering if you can also get rid of the line impeadance transformers. If the ART II has buffers in there, which it may not, you can dump them. I'm not sure though, just thinking out loud.
One more thing - lookout! You are about to get hooked at a tender age