With all due respects, your AV audio is likely to have already gone through baluns like these as they are extensively used in industry. They are cheap as they are well proven basic devices. You can buy the branded professional grade devices for a few $ more. Each to their own but others may not feel the need to over engineer the problem.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).