Check this out. I used RX10 and DeMIX Pro 4. This is a one minute sample, vocals only, 4 channel flac file, no LFE
https://mega.nz/file/GUJxhAQL#rUEITSIc6iLkoW3pF2Sbn7UF3_ciNwF3cNh8nQV6YP8
https://mega.nz/file/GUJxhAQL#rUEITSIc6iLkoW3pF2Sbn7UF3_ciNwF3cNh8nQV6YP8