As a rational justification…
If you ran the line output into a sound card, then maybe that could be used as a way to record what is there when playing nothing.
I was doing this yesterday, and also upgrading the OS on the computer to get a better analysis solution.
But I also try and have a choke hold on my wallet.
If the before and after of the addition of the Gutwire showed a change then we can determine the worth.
But if there is no change, then it would not be worth adding even it it were to be free.
The irrational part of us is strong, and can justify many things.