New User can only hear vocals, not guitars

[jeffdanielski]

So you both tried your instrument in the - functional - 'other' channel (the one that does produce sound with a mic) and no dice?

Couple obvious ones (sorry);
Did you adjust the input gain on your 2i2 for your guitars?
Is the 2i2 registering input from your instruments - so does the ring/button light up?

^If so^, is JK registering input on your instrument channel?
Is it real low by chance?
Did the channel accidentally get muted in JK? (easy to do/overlook)

Do you use Focusrite Control (2)?

>DM should be switched off btw. Like when using a daw, you listen to the output from the app/program - the mix.
So when not 'in a session' there should be no sound from either channel.

Hi Dimitri - My buddy and I are going to do another test paying attention to all the things you called out. I'll respond as soon as we've done it. Thanks again for your guidance.

Dimitri - Following are answers to your questions:

So you both tried your instrument in the - functional - 'other' channel (the one that does produce sound with a mic) and no dice?
*** Correct

Is the 2i2 registering input from your instruments - so does the ring/button light up?
*** The 2i2 is registering input and I can hear both channels if my headphones are plugged into the 2i2 itself. However, I cannot hear the input from either channel when I plug my headphones into my Mac Mini.

^If so^, is JK registering input on your instrument channel?
***JK is registering (visually) input from both channels.
Is it real low by chance?
***The levels seem to be normal--i.e., just by looking at where they top out, I would expect to hear them fine if I could hear them. 
Did the channel accidentally get muted in JK? (easy to do/overlook)
***No.

Do you use Focusrite Control (2)?
***I was not previously using Focusrite Control, but I downloaded and set it up. It is registering the input just as the 2i2 is. Should I have to change the inputs somehow in JK to rout them through Focusrite Control rather than coming directly from the physical 2i2? 

Thank you.