The ISO1 from Whirlwind is a line level audio-transformer device that can be used on console outputs or amplifier input-feeds for ground lifting to overcome buzz, and hum problems. In addition, use it to convert unbalanced 1/4" signals to balanced XLR signals for long cable runs.
Featuring both XLR and 1/4" TRS input/output jacks, the ISO1 uses Whirlwind's TRSP-600L transformer with a frequency response of ±1 db from 20 Hz to 20 kHz at +20 dBm input level. The two input jacks are connected in parallel with each other, as are the two output jacks. Use only one connector on each side at a time.
Also, the ground lift switch disconnects the ground between the input connectors and the output connectors when set to the LFT position. The ground is connected through when the switch is in the GND position.