I have been debating if I should get a Onkyo TX-SR501 or a TX-SR601. I will be running a JBL NSP1II in a small room that is 10X10. I know the TX-SR501 is more than enough for my room size, but I would like to know if it they're any advantages to getting the TX-SR601 apart from the more power? Will the 601 also rum hotter than the 501? Would also prefer if I didn't have to upgrade the receiver for more than 2 years. I can get the TX-SR501 for $200 brand new or the TX-SR601 for $315 refurbished. I will be upgrading from a Kenwood VR-505.