I just bought the Logitech Z906 sound system for my iMac Pro 2017 and I was quick to assume that it doesn't support a 5.1 surround sound output. So, I bought an external USB sound card (Startech.com ICUSBAUDIO7D), seemed to work at first, but when I ran through a Surround Test (found on youtube), I noticed that my back speakers were not playing and that their sound was coming out of the two front speakers. Upon further research, I learned that it doesn't support Mac OS.
So. I'm looking for a good quality 5.1 (or 7.1) Surround Sound external soundcard compatible with the iMac Pro 2017. Does anyone have any suggestions?
Startech.com 7.1 USB External Sound Card