I am a real novice when it comes to purchasing receivers and speakers so any help you could offer would be greatly appreciated. My plan is for a 5.1.4 setup. And just wondering which receivers would power all these channels without purchasing an extra power amp? At the moment interested in Yamaho RX-A3070, Denon AVR-X6400, Marantz SR7012 or Onkyo TX-RZ3100. Finding it difficult to choose between them. However have a demo booked this week to hear selection of speakers with Yamaha and Onkyo.