Stealthplug (guitar) and Linux issues

I have an old Stealthplug that I would like to use. I haven't used it in a while and don't have any Windows computers to set it up on. I could only find 1 article on the web for setting it up and that was on the Ubuntu forum back in 2012 but didn't provide enough info.

I plug it in, Ubuntu recognizes it and it shows up in the audio settings. I can set it up to act as the sound card and have videos on Youtube play through it. But I cannot get my guitar sounds to go thru it. I installed Jackd and Rakarack. I tried setting Jackd to connect the Stealthplug to Rakarack but still nothing. Does anyone have any tips?