I am sorry but there are not very many guitar players that have a need for three independent output jacks on their guitar. And someone more knowledgeable than I will probably provide a better answer. I am going to show you what appears in the Stadium App Editor (and similarly on the Stadium screen itelf).
There are the following inputs" None, Instrument 1, Instrument 2, Instrument 1+2, Mic, S.PDIF, Return 1, Return 2 Return 3, Return 4,Return 1/2, Return 3/4, USB 3/4, USB 4/5, and USB 7/8.
Both Instrument 1, 2 and 1+2 have the following input parameters:
Input Z has the following options: First Block, First Enabled (Block), 10K Ohm, 22K Ohm, 32K Ohm, 70K Ohm, 90K Ohm, 136K Ohm, 230K Ohm, and 1M Ohm.
Trim has the range from -24.0 dB to +6.0 dB
The Noise Gate is actually my preferred noise gate as it does a better job for me than the modelled Noise Gates in the box.
Return 1 only has the Trim Control and Noise Gate and not the Input Impedance values.
What Units are you considering that would have more than this? Just curious.
I hope that this at least helps.