Welcome to the forum!
What Pioneer amp do you have? You say that it has four HDMI outputs, but I'm guessing those are actually inputs. Most people will connect the HDMI outputs from their sources (e.g. your blu-ray player and Humax HDR) into their receivers, and then connect the one HDMI output from the receiver to their TV. I think that will be possible, but please let us know the model number of that Pioneer so that we can help you get this set up.