Does your patchbay convert unbalanced to balanced signals? Or, is it just grounding one of the two expected signal wires with the unbalanced signal from the KPA?
Using XLR to TRS cables would send balanced signals to your patchbay.
It looks like connecting a TS cable to that patch bay will cause the Ring of the TRS Output to be grounded. The TRS cable is sending an unbalanced signal to the interface.
If your interface needs a balanced signal to function correctly, that may be the problem.
XLR to TRS cables send a balanced signal.
One other thing to check:
What is the Input setting for the Interface?
Actually they are hot. 
I using 1/4" ts cables to connect my kemper to a balanced patchbay which then runs balanced lines to my interface.
I've checked the master output and raised it from -12 to 0, I'm still getting levels so low they don't register on a meter.
Then i add a compressor and boost the input and output gains until i get it to around -20dbfs.
What am I doing wrong? That signal hitting my interface should not be so low.
Might sound stupid but you probably just have to turn it up 
. Try turning up master volume (the knob to the right) If that does not help your volume may not be linked to that master volume knob. In that case press the master button.
Go to page two and set the volume manually for the output you have connected to your patchbay. HTH 
I have the same problem.
I connected the main outputs with balanced XLR cables to my UAD arrow XLR balanced inputs.
In line mode (which should be the right mode) I'm getting extremely low signals. In Mic mode I'm getting way too hot signals.
Volume on the Kemper is fully cranked up.
Which volume is fully cranked up? The Kemper has more than one volume. Did you check the Main Out volume in output menu? Is it linked to the master volume knob on the front? Also there's a -12dB tick box.
yes, the checked the output section and all volumes are fully up as well as the master volume on the front.
I'm assuming the Kemper sends line level
Hm...strange. Try "Init Globals" within the system menu.
is there an expression pedal or MIDI connected that could cause this?
please make a backup (!) and update to the latest release (7.0.9. at this point) if you haven't already
I have done some instigation and found the problem:
The UAD arrow interface does not accept line level signal when a XLR lead is connected. Only TRS jack leads can be used for line level.
I tried it with a jack lead and it works fine so the problem is with the UAD.
Thanks for your inputs though!!
