I want to just use my HD500 as a effects pedal board but have a problem. When I create a patch with effects and do not assign a model amp or pre-amp in the chain I get no sound. I assume that I am setting this up incorrectly. My guitar is hooked to HD500 Guitar in and I am running cable from HD500 1/4" Rmono out to front of combo amp. HD500 is set to run thru combo amp in settings. Any suggestions are greatly appreciated.