Ok I have an Asus M4A89GTD Pro/USB3 motherboard with the Realtek AC892 Audio chipset.
I have a EVGA GTX570 video card that I have connected to a Samsung LN-32C530 HDTV via HDMI. (Interestingly I was using one of its DVI output's and contrary to some posts in certain instances DVI can carry audio, as I had a DVI-HDMI cable connected PC to TV and I could select Audio out to the TV over the DVI port).
I have an old home stereo that I have connected to the speaker out (basic 2 channel stereo) on my motherboard, via a DAK Impedence matching transforming (highly recommend for a cheap way to connect PC to stereo without all the buzz and hum).
After going to the above HDTV for my PC monitor I realized the advantages of the HDMI connection to carry sound to the HDTV (vs. the LCD monitor only that it replaced and the desktop PC speakers that croaked).
Anyway just recently I got the bug to play audio over both the HDTV and my home stereo.
I encountered various forums and tried the typically referenced option of enabling the hidded recording device in Windows 7, "Stereo Mix" and selecting the "listen" and mapping it to my HDMI output to my TV. It worked...sort of. The problem was the intolerable delay of between half a second and a second.
I updated the Realtek drivers from Realtek directly (ASUS only vetted the original driver the motherboard shipped with), as some suggested that may remove the latency. It did not work.
Anyway for consumer use and non-professional applications I think the virtual audio cable from http://software.muzychenko.net/eng/vac.htm#history may satsify the majority of home users, barring purrist audiophiles.
Right now I am satisfied with the quality and sync using the "Virtual Audio Cable> Audio Repeater (Kernel Streaming version 1.82) with the Realtek HD Audio Stereo Input as the "Wave In" source and NVIDIA High Definition Audio (HDMI) as the wave out feature. It is set to Stereo with a 48kHz sample rate at 16 bits and a 5 ms buffer. The psychoacoustics of the delay in combination with the distances between the speakers in my living room is such that the delay/lag/latency is to me not just tolerable, but unnoticeable.
I am listening to the Lorde album as I type this, and had to adjust the levels as it sounded like the speakers in the TV were being over-driven. At first I thought maybe the software was showing a fault with sound degradation, but I think it was just the volume level was too high.
Anyway for a rough and dirty solution I have to say this virtual audio cable probam worked pretty well. I don't know how long the trial period is, but if it continues to work I'll likely buy it.
So I'd give it a try.