TOPIC:

Im using the UMIK with REW trying to characterize all 7 channels. Ive discovered my receiver (Denon AVR-X-4500H) does not have a analog input that would allow me to use REW as a audio input to selectively test 7.1 speakers (it has pre only for stereo).
REW has a HDMI multi channel approach, using ASIO4ALL v2 that wont work for me as my laptop sound card only has stereo.

But the "Offline" .wav file that REW can create might work if I can create a multi channel version of it........
I'd like to create a .wav file or multiple files originated from REW for "Offline" measurements that I can play from a USB port to test all 7.1 channels .
But REW only creates this "offline" file for the left and right channel only.
Am I missing something in REW or is there other software that would manipulate a offline .wav to create a multi channel version of the REW Offline file? By that I mean repeating the same offline file that can be played for each 7.1 channel?

Any tips appreciated. Thanks!.

Audacity will allow you to create and subsequently output a multichannel wav file based on an original stereo input wav file.
You simply copy and paste or duplicate a track as many times as you require. Or simply create empty (silent) tracks where necessary.
Nb - it is important to set Audacity preferences correctly to enable multichannell output.
Please refer to this Audacity help page

Can probably also be done with the sox remix option i.e. something like

sox input.wav output.wav remix 0 0 0 0 1 0 0 0

to create an 8-channel file with signal only in channel 5.

However if you can output via USB, why not just output directly in real time via USB?