writes "Use case: I have an high resolution LCD monitor connected via HDMI to my computer. In addition, I have an AV receiver capable of receiving multichannel PCM audio into HDMI input but said HDMI input only supports resolutions up to 1920x1080p so I don't want to route my display through the receiver. I would like to add a new HDMI output port to my computer with the intent to never output any video from that port, only multichannel PCM audio.
One would imagine that an USB device that pretends to be a multichannel USB audio card to the host and pretends to be HDMI source device to the AV receiver would be pretty cheap to build. Technically it would be an USB audio card to HDMI converter that does media conversion but does not change bitrate, bit depth or anything else.
Does such a product exists at all?"