Output level question

I am using the uTrack24 as follows:

The uTrack24 is used as a safety backup next to my DAW.
Inputs are connected to the (balanced) direct outputs of my mixer.
No problem so far. (Levels are perfectly matched with my DAW.)
But for certain reasons, I have to return the signal from the uTrack24 to the (unbalanced) insert return of the mixer. (The line inputs are uses by other sources.)
This gives a signal loss of 6 dB.
I am using only one ‘leg’ of each output.

To get the signal back to the correct level, there would be two (pretty expensive) options:
1: Add a 6 dB amplifier to each of the 24 outputs
2: Add 1:1 transformers between the balanced output of the uTrack24 and the unbalanced return.

In some cases, the electronically balanced outputs behave like a transformer; if the unused ‘leg’ is grounded, the level on the used ‘leg’ will then increase by 6 dB.
But when the output is a standard (OpAmp) inverted signal, this will harm the output stage. (If it is shorted.)

Is there someone who has a suggestion for raising the output level by 6 dB? Suggestions would be highly appreciated!