Review on 🔌 Sewell Sound Link: Bi-Directional Audio Extender up to 2000ft over Cat5e/Cat6, with 3.5mm & RCA Inputs/Outputs - Black by Joshua Castillo

Well it's a real isolated balun! I disassembled it just in case (see photo) and here they are: isolation transformers. You can also see in the photo that the traces are surrounded by a good ground plane with lots of vias to shield the signal. Don't confuse this product with $10 devices that plug RCA connectors directly into CAT twisted pairs. These cheaper devices don't protect your signal! These isolating transformers "float" in your audio signal so that it is no longer dependent on other potentials. This means that your audio signal is not disturbed by stray magnetic fields or differences in ground potential between your transmitting and receiving devices. Both can be important over long distances. It costs extra money to avoid 60Hz hum or other noise in your audio signal. Also, these baluns are passive, so you don't need to connect to the power supply.