I have got the same Yamaha RX-V661.
I use it optical-connected with my Sony tv; in this configuration, i can't control volume on TV remote, only on yamaha remote.
I've read that ARC-hdmi lets control volume on TV remote, but rx-V661 has no ARC.
Anyway, RX-V661 has got hdmi ports.
Any chance to control volume on Sony remote (using only one remote) ?