If I'm gaming on my PC monitor with the TV display off then there is no sound being sent to the A/V receiver over HDMI unless I have my main display hooked up through the receiver as well (hello input lag).
No, I went to great lengths to explain to you that I personally use HDMI audio without turning my TV on, which is exactly what you said you wanted to do...
And your receiver is only going to introduce lag if a) it's a piece of shit or b) you have it configured for a bunch of video enhancing options. I play PC games on my monitor or TV depending on my mood, and using my receiver-routed TV instead of a direct-connect monitor makes no difference.
Steam + PSN: PHJF