Yes, you should be able to do that. You want setup button/speakers/manual setup/amp assign. From there I had to change the assign mode to 11.1ch and a speaker layout to reflect it. Once you do that you should be able to scroll down to "Pre-out" and assign them to the front speakers.
*Edit: if you need to you can turn the extra channels off under "speaker config." and everything should work just like always.
