Is your AVR capable of passing HDMI while in standby? Why not use the AVR for all of your audio requirements? Have you considered an inexpensive HDMI port multiplier like this? One thing I am not sure of is how the port multiplier will report the audio capability to the PC if both display and AVR are active. For that case, you could use an HDMI switch and pass everything through the AVR or pass to the display only.
