Monitor output impedance and matching transformer

  • Anyone know what impedance the unbalanced-monitor output terminal is?
    I want to connect a 1:1 balancing transformer to combat some noise issues I'm having (yes i've tried the ground lift option)
    I've tested using a 600-600 ohm transformer and it does the trick but it would be better to match the impedance of the output, unless it turns out that is is around 600 ohms.
    There maybe some phase-shifting and altered frequency response as a result so any other suggestions are welcome.