Hey Joeman,
thanks for the motivation to help me.
Actually, when you just use the FreqBox as the only device in the MatrixBrutes insert channel, and you switch it between bypass and on, pushing the metal stomp button, there is quite the audible difference between the bypassed signal and the signal going through the FreqBox. Even when the Freq's Mix is fully turned to just the input signal, counterclockwise. There is just some high frequency context missing.
And since you can compare the sound so easily (by pressing the metal stomp knob), it is very clearly audible.
If you wanna give that a try, I would be thankful indeed!
Cheers!