For those looking for a Linux version of the SQ MixPad, Versions 1.5 and 1.6 of the Windows app run perfectly in Wine. Download the .zip file, extract it, and, in the directory you extracted it to, either open a terminal and type:
wine ‘SQ Mixpad [version] Installer.exe’
or right, click on the extracted file in your file manager and select Open With | Wine Installer