Say I had a Marshall style head/amp that was plugged into two separate speaker cabinets (i.e., a full stack). Are there effects that can be put between the head and cab running at "amp level" (as opposed to "line level")? For example, if I wanted to spread the two cabinets apart (stage right/stage left), and delay the signal to one cab by a few milliseconds to create sort of a faux stereo setup. Basically, create a wet/dry setup, but without the need for two amps. Does anything like that exist?