I'm actually doing the same thing, using a USB sound card for input and HDMI out for output. I asked the same question of John (REW author), how do you do a loopback calibration in this case, here was the exchange:http://www.hometheatershack.com/foru...tml#post506888
Originally Posted by fitzwaddle
I'm trying to use ASIO4ALL with two devices - USB sound card for mic input, and HDMI for output - so I can easily switch between measuring all 7 channels and sub without having to manually fiddle with wires. Seems to be working well, but I'm not really sure how to go about doing a loopback to calibrate the sound card, since input and output is handled by two devices. Does loopback even apply in this case, if so how would I go about it? The only way I can think of would be to calibrate the sound card itself - then take a measurement using the sound card, another measurement with the sound card in / HDMI out, and then manually subtract deltas and apply to the calibration file.
Appreciate any advice.
Originally Posted by JohnM
If you were determined and had enough control over the gain of the USB soundcard you could make a loopback connection from a line level output of your receiver (assuming the HDMI output is feeding a receiver) to the input of the USB soundcard. Could also do without a cal file, but make doubly sure that the signal from the mic is not making its way back to the output, if you speak into the mic you should not hear anything from the HDMI out.
For now, I'm just doing without the sound card calibration, and accepting that I could be off a little.