Hey TZ
They say that necessity is the mother of invention but you might be doing things the hard way
Does your console have direct outs?
Does your console have group outs?
Does your console have Auxiliary outs?
Any of these could give you a line level signal, from your specified channel, without dropping the signal from the channel strip.
For instance: guitar into channel 1 and aux 1 output sent to your Delta 1010LT H/W input. Dial up aux 1, only on that channel, and you are now sending signal to Sonar but still have signal to your monitors.
Cheers
Baron