Software Defined Home Theatre
I just saw this topic, I kind of have a similar setup to what he is describing.
Fan noise isn't a problem as I have efficient cooling and large fans (larger the fans lower the resonating frequency). Also when playing back 4k surround footage my pc CPU idles at 1% when the fans haven't even turned on yet! (I did this by creating a custom fan curve, very simple process if you have the right motherboard).
I knew I was going to be using the pc as a source for an amplifier for a home theatre so I saved up a bit more and bought a motherboard with really great DAC and real Nicheon (I think that was the name - they are the gold ones) capacitors.
The PC has 4 stereo outputs so I could add another 2 speakers for 7.1 If I wanted.
The Motherboards I recommended both have audiophile grade audio built in, and at a very reasonable price.
The low power Rizen/Athlon CPUs almost completely eliminate the need for big fans.
To be honest... home theatre duty is a very lazy task for a PC, these days.
I have it so it activates a macro in my overclocking software to lower the fan rpms on my graphics card and CPU cooler whilst turning all boosts off and giving a slight underclock. Due to the cooler I have, I can choose to underclock it a bit more and the heat sinks just dissipate enough of the heat. 🙂