I am considering replacing my two PSB Bookshelf speakes with Pioneers that get good reviews. Can I use the the 4 Receiver withPSB's as the rear surround ? Also I have an older Onkyo TX-SR30 with65 watts per channel. Is this adequate to drive the floorstanding speakers or do I need something stronger ? Is there an audible difference between the 100 and 200 watt Receivers ?