I would tough it out until the 978 comes out. It sounds like the 906 is on its last legs, but maybe not. The 978 will give you the flexibility to hook up anything you want. Since there is no 4K material out there, I would keep the c6500 until it died, especially if you want to save $$$ for the future.
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Music system Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD APC H15 Power Conditioner
TV System Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv
Home Theater System Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv Harmony ONE Blue Jeans and Monoprice interconnects APC H15 Power Conditioner